Purification and characterization of a low molecular weight endoxylanase from solid-state cultures of alkali-tolerant Aspergillus fischeri.
A low molecular weight, alkaline-stable endoxylanase (XylB) was purified to homogeneity from solid-state culture of Aspergillus fischeri Fxn1. XylB had a molecular mass of 13 kDa which is the lowest of reported xylanases. Optimal activity was at pH 6 and 55 degrees C. XylB was stable from pH 4.5 to 10 and up to 60 degrees C. It was non-glycosylated. The apparent K(m) and V(max) values of XylB on birch wood xylan were 0.53 mg ml(-1) and 0.2 mmol min-1 mg-1, respectively. The activity of XylB was not inhibited by Cd2+, Zn2+, Co2+, EDTA, iodoacetamide, beta-mercaptoethanol and acetic anhydride but strongly inhibited by 10 mm of N-bromosuccinimide, Hg2+, Pb2+ and p-hydroxymercuric benzoate. XylB is an endoxylanase since it hydrolysed xylan resulting the formation of xylo-oligomers but not of xylose residues.
Department of Microbial Technology, School of Biological Sciences, Centre for Excellence in Genomic Sciences, Madurai Kamaraj University, Madurai 625 021, India.
Sundar Rajan
SR
Senthilkumar
Balasubramaniem
B
Ashokkumar
Krishnan Chandra
KC
Raj
Paramasamy
P
Gunasekaran
D000468:Alkalies / Q000494:pharmacology; D001230:Aspergillus / Q000145:classification / Q000187:drug effects / Q000201:enzymology*; D018929:Cell Culture Techniques / Q000379:methods*; D004361:Drug Tolerance; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000302:isolation & purification*; D004789:Enzyme Activation; D004795:Enzyme Stability; D013045:Species Specificity; D013379:Substrate Specificity; D013696:Temperature; D014934:Wood; D014990:Xylans / Q000737:chemistry*
D000468:Alkalies; D014990:Xylans; D043364:Endo-1,4-beta Xylanases