PURIFICATION AND CHARACTERIZATION OF THERMOSTABLE ALPHA-AMYLASE-II FROM BACILLUS-SP-JF(2) STRAIN

Citation
Xz. Zhang et al., PURIFICATION AND CHARACTERIZATION OF THERMOSTABLE ALPHA-AMYLASE-II FROM BACILLUS-SP-JF(2) STRAIN, Enzyme and microbial technology, 16(11), 1994, pp. 985-990
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biothechnology & Applied Migrobiology
Journal title
ISSN journal
0141-0229
Volume
16
Issue
11
Year of publication
1994
Pages
985 - 990
Database
ISI
SICI code
0141-0229(1994)16:11<985:PACOTA>2.0.ZU;2-A
Abstract
Thermostable alpha-amylase from Bacillus sp-JF(2) strain was found to have three ee active components (named alpha-amylase I, II, and III) w ith molecular weights of 110,000, 140,000, and 300,000, respectively. alpha-Amylase II was isolated and purified in the current work by diff erent procedures from that for alpha-amylase I. alpha-Amylase II consi sts of two identical subunits (MW 70,000). The isoelectric point is 4. 7. The temperature optimum is at 90 degrees C and the pH optimum is 5. 5 for the enzyme activity. The half-life of the enzyme at 90 degrees C is 30 min, and the enzyme is stable over a pH range of 7.0-9.0. The K m value of the enzyme was estimated to be 3.3 mg ml(-1). A considerabl e difference in amino acid composition was observed between alpha-amyl ase I and alpha-amylase II. The alpha-helix content of alpha-amylase I I was calculated to be 51% from the circular dichroism spectrum. The n umber of Ca2+ binding to each molecule of alpha-amylase II was determi ned to be 10 by atomic absorption.