Chemical modification of lysine residues in Bacillus licheniformis alpha-amylase: conversion of an endo- to an exo-type enzyme.
The lysine residues of Bacillus licheniformis alpha-amylase (BLA) were chemically modified using citraconic anhydride or succinic anhydride. Modification caused fundamental changes in the enzymes specificity, as indicated by a dramatic increase in maltosidase and a reduction in amylase activity. These changes in substrate specificity were found to coincide with a change in the cleavage pattern of the substrates and with a conversion of the native endo- form of the enzyme to a modified exo- form. Progressive increases in the productions of rho-nitrophenol or glucose, when para nitrophenyl-maltoheptaoside or soluble starch, respectively, was used as substrate, were observed upon modification. The described changes were affected by the size of incorporated modified reagent: citraconic anhydride was more effective than succinic anhydride. Reasons for the observed changes are discussed and reasons for the effectivenesses of chemical modifications for tailoring enzyme specificities are suggested.
Habibi
Azadeh Ebrahim
AE
Institute of Biochemistry and Biophysics, University of Tehran. P. O. Box: 13145-1384, Tehran, Iran.
Khajeh
Khosro
K
Nemat-Gorgani
Mohsen
M
D000812:Anhydrides / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D008239:Lysine / Q000737:chemistry*; D015394:Molecular Structure; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry / Q000378:metabolism
D000812:Anhydrides; D001426:Bacterial Proteins; D000516:alpha-Amylases; C501919:alpha-amylase, Bacillus licheniformis; D005947:Glucose; D008239:Lysine