Crystal Structure of Agmatinase Reveals Structural Conservation and Inhibition Mechanism of the Ureohydrolase Superfamily

Abstract

Agmatine is the product of arginine decarboxylation and can be hydrolyzed by agmatinase to putrescine, the precursor for biosynthesis of higher polyamines, spermidine, and spermine. Besides being an intermediate in polyamine metabolism, recent findings indicate that agmatine may play important regulatory roles in mammals. Agmatinase is a binuclear manganese metalloenzyme and belongs to the ureohydrolase superfamily that includes arginase, formiminoglutamase, and proclavaminate amidinohydrolase. Compared with a wealth of structural information available for arginases, no three-dimensional structure of agmatinase has been reported. Agmatinase from Deinococcus radiodurans, a 304-residue protein, shows ∼33% of sequence identity to human mitochondrial agmatinase. Here we report the crystal structure of D. radiodurans agmatinase in Mn2+-free, Mn2+-bound, and Mn2+-inhibitor-bound forms, representing the first structure of agmatinase. It reveals the conservation as well as variation in folding, oligomerization, and the active site of the ureohydrolase superfamily. D. radiodurans agmatinase exists as a compact homohexamer of 32 symmetry. Its binuclear manganese cluster is highly similar but not identical to the clusters of arginase and proclavaminate amidinohydrolase. The structure of the inhibited complex reveals that inhibition by 1,6-diaminohexane arises from the displacement of the metal-bridging water. Agmatine is the product of arginine decarboxylation and can be hydrolyzed by agmatinase to putrescine, the precursor for biosynthesis of higher polyamines, spermidine, and spermine. Besides being an intermediate in polyamine metabolism, recent findings indicate that agmatine may play important regulatory roles in mammals. Agmatinase is a binuclear manganese metalloenzyme and belongs to the ureohydrolase superfamily that includes arginase, formiminoglutamase, and proclavaminate amidinohydrolase. Compared with a wealth of structural information available for arginases, no three-dimensional structure of agmatinase has been reported. Agmatinase from Deinococcus radiodurans, a 304-residue protein, shows ∼33% of sequence identity to human mitochondrial agmatinase. Here we report the crystal structure of D. radiodurans agmatinase in Mn2+-free, Mn2+-bound, and Mn2+-inhibitor-bound forms, representing the first structure of agmatinase. It reveals the conservation as well as variation in folding, oligomerization, and the active site of the ureohydrolase superfamily. D. radiodurans agmatinase exists as a compact homohexamer of 32 symmetry. Its binuclear manganese cluster is highly similar but not identical to the clusters of arginase and proclavaminate amidinohydrolase. The structure of the inhibited complex reveals that inhibition by 1,6-diaminohexane arises from the displacement of the metal-bridging water. The classic pathway for polyamine biosynthesis proceeds from l-arginine to putrescine by the action of arginase and ornithine decarboxylase. Arginase cleaves the terminal guanidine moiety of l-arginine to produce ornithine and urea, and ornithine decarboxylase in turn converts ornithine into putrescine by decarboxylation (Fig. 1A) (1Wu G. Morris S.M. Biochem. J. 1998; 336: 1-17Crossref PubMed Scopus (2271) Google Scholar). Bacteria, plants, and other lower species synthesize polyamines via a second distinct pathway where arginine is first decarboxylated to agmatine (1-amino-4-guanidinobutane) by arginine decarboxylase followed by the removal of urea to form putrescine by agmatinase (agmatine ureohydrolase, E.C. 3.5.3.11) (Fig. 1A) (2Satishchandran C. Boyle S.M. J. Bacteriol. 1986; 165: 843-848Crossref PubMed Scopus (54) Google Scholar, 3Tabor C.W. Tabor H. Annu. Rev. Biochem. 1984; 53: 749-790Crossref PubMed Scopus (3280) Google Scholar). Reports on the arginine decarboxylase activity in kidney (4Lotrie M.J. Novotny W.F. Peterson O.W. Vallon V. Malvey K. Mendonca M. Satriano J. Insel P. Thomson S.C. Blantz R.C. J. Clin. Investig. 1996; 97: 413-420Crossref PubMed Scopus (160) Google Scholar) and brain (5Regunathan S. Feinstein D.L. Raasch W. Reis D.J. Neuroreport. 1984; 6: 1897-1900Crossref Scopus (77) Google Scholar) and the agmatinase activity in rat brain (6Sastre M. Regunathan S. Reis D.J. J. Neurochem. 1996; 67: 1761-1765Crossref PubMed Scopus (131) Google Scholar) and a mouse macrophage cell line (7Sastre M. Galea E. Feinstein D. Reis D.J. Regunathan S. Biochem. J. 1998; 330: 1405-1409Crossref PubMed Scopus (62) Google Scholar) suggest that this alternative pathway for polyamine biosynthesis is also functional in mammals. Agmatine is widely distributed in a number of mammalian tissues including brain, kidney, stomach, intestine, and aorta (8Raasch W. Regunathan S. Li G. Reis D.J. Life Sci. 1995; 56: 2319-2330Crossref PubMed Scopus (250) Google Scholar). Recent discoveries suggest that, in mammals, agmatine may possess functions other than that of a metabolic intermediate for polyamines (9Gilad G.M. Wollam Y. Iaina A. Rabey J.M. Chernihovsky T. Gilad V.H. Neuroreport. 1996; 7: 1730-1732Crossref PubMed Scopus (36) Google Scholar, 10Iyer R.K. Kim H.K. Tsoa R.W. Grody W.W. Cederbaum S.D. Mol. Genet. Metab. 2002; 75: 209-218Crossref PubMed Scopus (85) Google Scholar, 11Mistry S.K. Burwell T.J. Chambers R.M. Rudolph-Owen L. Spaltmann F. Cook W.J. Morris S.M. Am. J. Physiol. 2002; 282: G375-G381Crossref PubMed Scopus (74) Google Scholar) and that it has potential as a treatment of chronic pain, addictive states, and brain injury (12Reis D.J. Regunathan S. Trends Pharmacol. Sci. 2000; 21: 187-193Abstract Full Text Full Text PDF PubMed Scopus (388) Google Scholar). Its effects include inhibition of cell proliferation, stimulation of glomerular filtration rate in kidney, activation of constitutive nitric-oxide synthase, and inhibition of inducible nitric-oxide synthase (11Mistry S.K. Burwell T.J. Chambers R.M. Rudolph-Owen L. Spaltmann F. Cook W.J. Morris S.M. Am. J. Physiol. 2002; 282: G375-G381Crossref PubMed Scopus (74) Google Scholar). Agmatine has also been proposed to act as a possible neurotransmitter/neuromodulator. It binds to α2-adrenoreceptors and imidazoline-binding sites and blocks N-methyl-d-aspartate receptor channels and other ligandgated cationic channels (12Reis D.J. Regunathan S. Trends Pharmacol. Sci. 2000; 21: 187-193Abstract Full Text Full Text PDF PubMed Scopus (388) Google Scholar, 13Reis D.J. Regunathan S. Ann. N. Y. Acad. Sci. 1999; 881: 65-80Crossref PubMed Scopus (87) Google Scholar). Changes in activity or expression of agmatinase could play an important role in regulating the physiological actions of agmatine. Agmatinase is a binuclear manganese metalloenzyme and belongs to the ureohydrolase superfamily (14Ouzounis C.A. Kyrpides N.C. J. Mol. Evol. 1994; 39: 101-104Crossref PubMed Scopus (71) Google Scholar, 15Sekowska A. Danchin A. Risler J.L. Microbiology. 2000; 146: 1815-1828Crossref PubMed Scopus (56) Google Scholar). Other members of this superfamily include arginase, formiminoglutamase, and proclavaminate amidinohydrolase (PAH). 1The abbreviations used are: PAH, proclavaminate amidinohydrolase; DR, Deinococcus radiodurans; r.m.s.d., root mean square deviation. We suggest using the term “ureohydrolase superfamily,” because it is more suited to describe a variety of substrates that its members hydrolyze (Fig. 1B) than the term “arginase superfamily.” An analysis of the evolutionary relationship among ureohydrolase superfamily enzymes indicates that the sequence similarity trees separate agmatinases from arginases including Deinococcus radiodurans (DR) agmatinase (15Sekowska A. Danchin A. Risler J.L. Microbiology. 2000; 146: 1815-1828Crossref PubMed Scopus (56) Google Scholar). It was suggested that the arginase pathway of polyamine biosynthesis is likely to have evolved later than the pathway involving arginine decarboxylase and agmatinase (15Sekowska A. Danchin A. Risler J.L. Microbiology. 2000; 146: 1815-1828Crossref PubMed Scopus (56) Google Scholar). Among the ureohydrolase superfamily members, crystal structures are available for rat liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), human extrahepatic arginase II (17Cama E. Colleluori D.M. Emig F.A. Shin H. Kim S.W. Kim N.N. Traish A.M. Ash D.E. Christianson D.W. Biochemistry. 2003; 42: 8445-8451Crossref PubMed Scopus (126) Google Scholar), arginase from Bacillus caldovelox (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar), and from J.M. H. Biochem. J. 2002; PubMed Google Scholar). the or structure and the active site with a binuclear manganese no three-dimensional structure of agmatinase has been reported. The of the human agmatinase a with a mitochondrial sequence the was R.K. Kim H.K. Tsoa R.W. Grody W.W. Cederbaum S.D. Mol. Genet. Metab. 2002; 75: 209-218Crossref PubMed Scopus (85) Google Scholar, 11Mistry S.K. Burwell T.J. Chambers R.M. Rudolph-Owen L. Spaltmann F. Cook W.J. Morris S.M. Am. J. Physiol. 2002; 282: G375-G381Crossref PubMed Scopus (74) Google Scholar). The sequence of human agmatinase is more similar to agmatinases than to human arginases I and II sequence identity and agmatinase shows a of sequence to human mitochondrial agmatinase but it shows lower and for and of sequence to human arginases I and arginase shows and for and of sequence to human arginases I and it is similar to human and agmatinases and and the three-dimensional structure of agmatinase be a for human mitochondrial agmatinase. Here we have the crystal structure of agmatinase in Mn2+-free, Mn2+-bound, and Mn2+-inhibitor-bound It reveals that agmatinase exists as a compact homohexamer of 32 and has a binuclear manganese cluster that is highly similar to of arginase and proclavaminate amidinohydrolase. The structure of the in complex with an of into and inhibition and agmatinase with and was and in the Mn2+-inhibitor-bound form in the of 1,6-diaminohexane as S.M. Kim Kim H.K. S.W. PubMed Scopus Google Scholar). we have of the the of and of the but also in the of and in the of and of the and on a of as for the Mn2+-inhibitor-bound form S.M. Kim Kim H.K. S.W. PubMed Scopus Google Scholar). The with the and W. PubMed Scopus Google Scholar). by using a of from S. followed by was using the P.D. G.M. P. R.W. J. M. T. 1998; PubMed Scopus Google Scholar). of the of in the the of the I the for and on and in to the where is the of is the and is the of where is for a not used for structure and is for the of in to the where is the of is the and is the of where is for a not used for structure and is for the in a The was by the 2000; Scopus Google Scholar) to an for of the of the with of the sequence was using the S.W. M. A. PubMed Scopus Google Scholar). The was with the and of and The in of using followed by and The of the Mn2+-inhibitor-bound for of the and in the and of and for the The includes of agmatinase and an from the this was used to the and structures and ureohydrolase activity was by a of the by N. V. M. E. P. J. Biochem. 1999; PubMed Scopus Google Scholar) for the of of agmatinase a of was into a and agmatine in a of for of a of and and of in well by and in a for was by the The of urea was by with a urea The of agmatinase was by using the as the the agmatinase The was by of agmatinase is in with the of manganese and the the active The structures of the in the of the crystal are identical to The root mean square and we of of other for of the crystal The of and the in no in the The is the and the and Mn2+-inhibitor-bound and the and Mn2+-inhibitor-bound structures of is into a of of and is of an with on (Fig. The is by rat liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), human liver arginase II (17Cama E. Colleluori D.M. Emig F.A. Shin H. Kim S.W. Kim N.N. Traish A.M. Ash D.E. Christianson D.W. Biochemistry. 2003; 42: 8445-8451Crossref PubMed Scopus (126) Google Scholar), caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar), and from S. J.M. H. Biochem. J. 2002; PubMed Google Scholar). The of the are in the or to the in a that a of and of the and of and the other (Fig. and are and a agmatinase and S. PAH, are and the root mean square is for identity are more for the sequence of agmatinase with rat liver arginase I and caldovelox The root mean square are for rat liver arginase I sequence identity and for caldovelox arginase sequence identity agmatinase has and and and The first is of a highly sequence (Fig. and is to agmatinase. The second and is of the in the ureohydrolase superfamily (15Sekowska A. Danchin A. Risler J.L. Microbiology. 2000; 146: 1815-1828Crossref PubMed Scopus (56) Google Scholar). of rat liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar), and from S. J.M. H. Biochem. J. 2002; PubMed Google Scholar) also a The of is to the of and the of is to the of (Fig. of is important in the active site and of the for is of the is also well and its in rat and in was for with the of the (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar, M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). arginases are (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), arginases are Grody W.W. Cederbaum S.D. Biochem. Physiol. 1996; PubMed Scopus Google Scholar). the of caldovelox arginase, the crystal structure possible (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). was in crystal and and was to be the in was in crystal form I of in that of the crystal S. exists as a in and J.M. H. Biochem. J. 2002; PubMed Google Scholar). The of was with agmatinase being a or in S.M. Kim Kim H.K. S.W. PubMed Scopus Google Scholar). The crystal structure of agmatinase shows that it exists as a compact of 32 with of (Fig. The of the no in the or the The is the and the and Mn2+-inhibitor-bound and the and Mn2+-inhibitor-bound structures for in a is by to the other a of with of the other (Fig. and S. has a similar of J.M. H. Biochem. J. 2002; PubMed Google Scholar), the in enzymes are the of of the and of that in S. and caldovelox arginase that are by the and is a of the (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). a The of in the of agmatinase is more similar to that in S. than that in rat liver arginase I and caldovelox arginase (Fig. and agmatinase a of the S. J.M. H. Biochem. J. 2002; PubMed Google Scholar), rat liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), and caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar) and The of agmatinase to the the and and the and E. it is not of the and (Fig. and and of the in and and of the in (Fig. a of S. is to the by the of the of the to a to the active rat liver arginase an of the in the (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar). caldovelox arginase, this is but a similar to that of the rat is (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). active site of agmatinase a and a binuclear manganese cluster the of a active site on of the (Fig. the of the manganese cluster with the that the metal-bridging is and the is The is for the structure and for the in the it is in the Mn2+-inhibitor-bound structure and are the of the in and and Ash D.E. Biochemistry. 1995; PubMed Scopus Google Scholar). The was for of the and we that it is is to the of the and the of the The manganese in caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar) and S. J.M. H. Biochem. J. 2002; PubMed Google Scholar) are The in the crystal structures of rat liver arginase I in complex with a of and E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). from to in the crystal structures of and of rat liver arginase I E. Emig F.A. Ash D.E. Christianson D.W. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). The from in the structure of rat liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar) to in the complex N.N. Emig F.A. S.K. D.W. Morris S.M. Ash D.E. Traish A. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar), but the is not of this it was that the of rat liver arginase I the metal-bridging E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). the but structure of the first that is more in the active site is with square by and and a (Fig. The second is by and and the in a the manganese in the in the the is the manganese The and are among members of the ureohydrolase superfamily by the in (15Sekowska A. Danchin A. Risler J.L. Microbiology. 2000; 146: 1815-1828Crossref PubMed Scopus (56) Google Scholar). the of of the are to the to the of the a to is in turn to and to and a to the of is to the of and to and a is in turn to liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar), and from S. J.M. H. Biochem. J. 2002; PubMed Google Scholar) also a binuclear manganese cluster highly similar to that of agmatinase. is a in the of in of agmatinase is with square in the structure (Fig. manganese in caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar) and S. J.M. H. Biochem. J. 2002; PubMed Google Scholar) have with an the for rat liver arginase is with The of was to be square in the structure (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar), but it that the site on may a a that is for and E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar, The of of of Scholar). the structure of the metal-bridging is the with the and of and (Fig. are in the of and the is than the by to the The may on the of the structure of agmatinase of the is likely to be a The in the was also in the caldovelox arginase structure (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar) in the is with the of and The in caldovelox arginase are with the being a (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar, D.W. Annu. Rev. Biochem. 1999; PubMed Scopus Google Scholar). the structures of rat liver arginase I (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar) and S. J.M. H. Biochem. J. 2002; PubMed Google Scholar), the is the with an of or the may be J.M. H. Biochem. J. 2002; PubMed Google Scholar). a of the structures of rat liver arginase and of the binuclear manganese cluster by the metal-bridging E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). and the structure of agmatinase in complex with 1,6-diaminohexane to into and inhibition the among that inhibited agmatinase Google Scholar). shows the of agmatinase the active to its The of the active site is well suited for the as well as the The an with to and the other to are in turn to and the of and the of the active site (Fig. The of the not with the but its is for to be in It is that the is the is The structure of the inhibited complex shows that inhibition by 1,6-diaminohexane arises from the displacement of the metal-bridging water. of complex are also in with the of on rat liver arginase I Ash D.E. Biochemistry. 1998; PubMed Scopus Google Scholar), suggest the of the by the terminal of as a and the of the the site of the agmatinase active the of 1,6-diaminohexane was to the a of and for the it was from and The of the to the of was from and and from and (Fig. The to the active site of the into the of manganese The have been to the of the it been into the this is for on the of the (Fig. structures of the of rat liver arginase I E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar, N.N. Emig F.A. S.K. D.W. Morris S.M. Ash D.E. Traish A. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar, E. Colleluori D.M. S. J.L. D. Ash D.E. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar, D. Kanyo Z.F. R.C. Ash D.E. Christianson D.W. J. Am. Scopus Google Scholar, Kim N.N. Traish A.M. Christianson D.W. 1999; 6: PubMed Scopus (160) Google Scholar) and human arginase II (17Cama E. Colleluori D.M. Emig F.A. Shin H. Kim S.W. Kim N.N. Traish A.M. Ash D.E. Christianson D.W. Biochemistry. 2003; 42: 8445-8451Crossref PubMed Scopus (126) Google Scholar) and caldovelox arginase was in complex with the and its (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). of the active sites of ureohydrolase superfamily enzymes shows that the site where the of the substrates binds is well the of the active site from other (Fig. Compared with the active sites of rat liver arginase I and caldovelox arginase, the active site of agmatinase in (Fig. the the and the and the of agmatinase was not in or It a from arginases and in and The of caldovelox arginase the (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). the other and to to the structural for (Fig. the caldovelox arginase the of arginine was to and and to that in turn by and (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). the rat arginase complex the and to and E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). the 1,6-diaminohexane the and the active site the of to that with the in caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar), was more and similar not (Fig. The is agmatine and arginine (Fig. The was to in turn to and and the of the active site of agmatinase. of of the by a of with is similar to that in caldovelox arginase (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar) and rat liver arginase I E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). caldovelox arginase, the of arginine was to and and was by potential and (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). the rat arginase complex the of arginine to and E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). with the not the active site the and of to the of caldovelox arginase, a of the (Fig. of the of sequence similarity agmatinase and human mitochondrial agmatinase (Fig. we have a of the human by The mitochondrial sequence the and the sequence similarity to agmatinase not that the in a from (Fig. in the active site of human agmatinase well to of in and the and in the of the active site where the of agmatinase are in other and of the human with the could similar with a as in agmatinase we the structural in the active sites of agmatinase and human agmatinase to be and we that the and of human mitochondrial agmatinase be highly similar to of agmatinase. for structure has important for the of the ureohydrolase superfamily Among this rat liver arginase I has been the of structural and indicate a for arginine (16Kanyo Z.F. Scolnick L.R. Ash D.E. Chistianson D.W. Nature. 1996; 383: 554-557Crossref PubMed Scopus (400) Google Scholar, D.W. Annu. Rev. Biochem. 1999; PubMed Scopus Google Scholar). inhibited structure is with this in the metal-bridging as a and the arginine a not the of the to the on the proposed arginase and and by (17Cama E. Colleluori D.M. Emig F.A. Shin H. Kim S.W. Kim N.N. Traish A.M. Ash D.E. Christianson D.W. Biochemistry. 2003; 42: 8445-8451Crossref PubMed Scopus (126) Google Scholar, E. S. J.L. S. Emig F.A. Ash D.E. D. Christianson D.W. Biochemistry. PubMed Scopus Google Scholar). on an alternative was proposed Ash D.E. Biochemistry. 1998; PubMed Scopus Google Scholar). of the to a manganese and of the as the arginase from the arginine is to its terminal not (18Bewley M.C. Jeffrey P.D. Patchett M.L. Kanyo Z.F. Baker 1999; 7: Full Text Full Text PDF PubMed Scopus Google Scholar). The be in the arginase from The 1,6-diaminohexane is to its terminal in complex the is a to be as to the site of agmatinase active a well was to the of the a of and and was also to and (Fig. could play the role of the to in rat liver arginase that was proposed to act as a a to the of the product and a from the D.W. Annu. Rev. Biochem. 1999; PubMed Scopus Google Scholar). It was in structures of agmatinase and was a of because arginases I and PAH, and human agmatinase a the of The of agmatinase was active with the that the of a this is not for the of agmatinase to of was to the agmatinase activity was to of the activity in for agmatine N. J. M. V. J. P. E. Biochem. 1999; PubMed Scopus Google Scholar). 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