Conformational destabilization of Bacillus licheniformis α-amylase induced by lysine modification and calcium depletion.

نویسندگان

  • Cheau Yuaan Tan
  • Raja Noor Zaliha Binti Raja Abdul Rahman
  • Habsah Abdul Kadir
  • Saad Tayyab
چکیده

Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔG(D)(H(2)O) values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔG(D)(H(2)O) value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Two-step purification and partial characterization of an extra cellular α-amylase from Bacillus licheniformis

The aim of this study was production and partial purification of α-amylase enzyme by Bacillus licheniformis. B. Licheniformis was allowed to grow in broth culture for purpose of inducing α-amylase enzyme. Optimal conditions for amylase production by B. Licheniformis are incubation period of 120 h, temperature of 37 °C and pH 7.0. The α-amylase enzyme was purified by ion exchange chromatography ...

متن کامل

Single Step Purification of Novel Thermostable and Chelator Resistant Amylase from Bacillus Licheniformis RM44 by Affinity Chromatography

Bacillus licheniformis RM44 was isolated from hot spring near Karachi and screened forthe production of extracellular amylase Amy RM44. Amy RM44 was purified to homogeneityon a single step by affinity chromatography using insoluble corn starch. The molecular weightof Amy RM44 was estimated to be 66 kDa by SDS–PAGE and zymographic analysis. Nine foldpurification was achieved with the specific ac...

متن کامل

Single Step Purification of Novel Thermostable and Chelator Resistant Amylase from Bacillus Licheniformis RM44 by Affinity Chromatography

Bacillus licheniformis RM44 was isolated from hot spring near Karachi and screened forthe production of extracellular amylase Amy RM44. Amy RM44 was purified to homogeneityon a single step by affinity chromatography using insoluble corn starch. The molecular weightof Amy RM44 was estimated to be 66 kDa by SDS–PAGE and zymographic analysis. Nine foldpurification was achieved with the specific ac...

متن کامل

Does recovery in the spectral characteristics of GdnHCl-denatured Bacillus licheniformis α-amylase due to added calcium point towards protein stabilization?

Treatment of Bacillus licheniformis α-amylase (BLA) with guanidine hydrochloride (GdnHCl) produced both denatured and aggregated forms of the enzyme as studied by circular dichroism, fluorescence, UV difference spectroscopy, size exclusion chromatography (SEC), and enzymatic activity. The presence of CaCl(2) in the incubation mixture produced significant recovery in spectral signals, being comp...

متن کامل

Codon Optimization Significantly Improves the Expression Level of α-Amylase Gene from Bacillus licheniformis in Pichia pastoris

α-Amylase as an important industrial enzyme has been widely used in starch processing, detergent, and paper industries. To improve expression efficiency of recombinant α-amylase from Bacillus licheniformis (B. licheniformis), the α-amylase gene from B. licheniformis was optimized according to the codon usage of Pichia pastoris (P. pastoris) and expressed in P. pastoris. Totally, the codons enco...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Acta biochimica Polonica

دوره 58 3  شماره 

صفحات  -

تاریخ انتشار 2011