Enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by poly(aspartic acid) hydrolases-1 and 2 from Sphingomonas sp. KT-1.
The enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by PAA hydrolase-1 and PAA hydrolase-2 (purified from Sphingomonas sp. KT-1) was performed to elucidate the mechanism of the microbial degradation by Sphingomonas sp. KT-1 of the thermally synthesized alpha,beta-poly(D,L-aspartic acid) (tPAA). GPC analysis of the hydrolyzed products of alpha- and beta-tetra(L-aspartic acid)s by PAA hydrolase-1 has showed that PAA hydrolase-1 is capable of hydrolyzing only the specific amide bonds between beta-aspartic acid units. The RP-HPLC analysis of the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s (4 and 5 mers) by PAA hydrolase-1 has suggested that the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s occurs via an endo-mode cleavage. In contrast, PAA hydrolase-2 hydrolyzed both alpha- and beta-oligo(L-aspartic acid)s via an exo-mode cleavage to yield L-aspartic acid as a final product. A kinetic study on the enzymatic hydrolysis of alpha-oligo(L-aspartic acid)s (3 to 7 mers) by PAA hydrolase-2 has indicated that Km values are almost independent of the number of monomer units in oligomers of 4 to 7 mers, while that Vmax values are markedly dependent on the chain length and show a maximum value at 5 mer.
Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan. thiraish@postman.riken.go.jp
Tomohiro
T
Hiraishi
Mariko
M
Kajiyama
Ichiro
I
Yamato
Yoshiharu
Y
Doi
D001224:Aspartic Acid; D001704:Biopolymers; D006868:Hydrolysis; D007700:Kinetics; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000737:chemistry*; D020578:Sphingomonas / Q000201:enzymology*
D001704:Biopolymers; D009842:Oligopeptides; D010455:Peptides; D011506:Proteins; C499773:alpha,beta-poly(aspartic acid); C017645:polyaspartate; D001224:Aspartic Acid; D012697:Serine Endopeptidases; C473051:poly(aspartic acid) hydrolase