Evidence that cleavage of the precursor enzyme by autocatalysis caused secretion of multiple amylases by Aspergillus niger

Abstract

The observation that a mutant strain of Aspergillus niger isolated for protease overproduction accumulated Takaamylase supported an earlier report that processing of the precursor amylase by protease resulted in the secretion of multiple amylases. Studies using a mutant strain revealed that such processing was not due to aspergillopepsin but to autocatalysis by an inherent protease activity of the precursor and glucoamylase. Alignment of protease sequences with glucoamylase showed regions of consensus with serine carboxypeptidase of A. niger. Thus point mutations in this region due to ultraviolet radiation apparently caused the mutant to evolve with enhanced protease activity that degraded the precursor and accumulated Takaamylase. ß

Glucose released by hydrolytic activity of amylase influences the pigment synthesis in Penicillium sp NIOM‐02

“…Amylase activities were detected accordingly Ravi‐Kumar et al . as zone of clearance after staining with iodine/iodide solution (0.6 g I 2 and 6 g KI l −1 ).…”

Pigment and amylase production in Penicillium sp NIOM‐02 and its radical scavenging activity

“…After electrophoresis, the amylase proteins were re‐natured by incubating the gel in acetate buffer (0.1 m , pH 4.3) at 30 °C for 90 min. Amylase activities were detected accordingly Ravi‐Kumar et al. (2004) as zone of clearance after staining with iodine/iodide solution (0.6 g I 2 and 6 g KI L −1 ).…”

The optimized production, purification, characterization, and application in the bread making industry of three acid‐stable alpha‐amylases isoforms from a new isolated Bacillus subtilis strain US586

“…Amylases could be produced by a variety of micro‐ and macroorganisms. However, many amylases isoforms could be derived from Bacillus , Pseudomonas and Aspergillus species (Maalej, Ben Ayed, Ghorbel‐Bellaaj, Nasri, & Hmidet, ; Ravi‐kumar, Venkatesh, & Umesh‐kumar, ; Sahnoun et al, ). The number of those forms varies according to the amylase‐producing strain and their appearance depends on the extracellular factors including halophilic medium environments and protease cleaving (Dubey, Suresh, Kavitha, Karanth, & Umesh‐Kumar, ).…”

“…The number of those forms varies according to the amylase‐producing strain and their appearance depends on the extracellular factors including halophilic medium environments and protease cleaving (Dubey, Suresh, Kavitha, Karanth, & Umesh‐Kumar, ). For instance, Aspergillus niger was reported to produce three α‐amylases with different molecular masses by the autoproteolysis of one precursor (Ravi‐kumar et al, ). B. licheniformis ATCC 9945a was also observed to generate six amylase isoforms (Natasa, Josep, & Zoran, ), while only two isoforms with the same physicochemical properties were delivered by Bacillus subtilis X‐23 through carboxyl truncation (Kohji et al, ).…”

“…For instance, Aspergillus niger was reported to produce three αamylases with different molecular masses by the autoproteolysis of one precursor (Ravi-kumar et al, 2004). B. licheniformis ATCC 9945a was also observed to generate six amylase isoforms (Natasa, Josep, & Zoran, 2011), while only two isoforms with the same physicochemical properties were delivered by Bacillus subtilis X-23 through carboxyl truncation (Kohji et al, 1999).…”