ISSN:
0138-4988
Keywords:
Life Sciences
;
Life Sciences (general)
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Process Engineering, Biotechnology, Nutrition Technology
Notes:
The cellulase complex of the fungus Aspergillus niger (strain CBS 554.65 = ATCC 16 888) was fractionated by gel filtration yielding six pronounced peaks. Only proteins from the fraction corresponding to the first peak (96 kDa) showed β-glucosidase activity vs. the substrate 4-nitrophenyl-β-D-glucopyranoside (pNPG). These proteins have been fractionated by chromatofocusing, yielding two β-glucosidases (I and II) which are shown to be homogeneous in isoelectric focusing experiments (pI = 4.6 and 3.8, respectively). Kinetic experiments with pNPG, MU-glucopyranoside and cellobiose revealed that both types of β-glucosidases behave like aryl-β-glucosidases. β-Glucosidase-I acting on pNPG exhibits a split kinetics characterized by high and low substrateconcentration kinetics which are differentiated by different values of V and of Km. In addition, β-glucosidase-II is shown to be an exo-glucohydrolase as deduced from experiments with MU-cellobiopyranoside.Experimental features should be emphasized; usual soft-gel ion-exchange materials did not work in the chromatofocusing separation of the two β-glucosidases, in contrast to the 10μ-Si 500 = DEAE exchange material (Serva) typically used in HPLC-experiments. Furthermore, protein content determinations based on different procedures yielded widely differing values.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/abio.370090219
