The understanding that enzymatic degradation of fruit pectin can clarify juices and improve juice yields resulted in the search for microbial pectinases and application in vegetable- and fruit-processing industries. Identified enzymes were classified on the basis of their catalytic activity to pectin or its derivatives and in terms of industrial use. Discovery of gene sequences that coded the enzymes, protein engineering, and molecular biology tools resulted in defined microbial strains that over-produced the enzymes for cost-effective technologies. Recent perspectives on the use of pectin and its derivatives as dietary fibers suggest enzymatic synthesis of the right oligomers from pectin for use in human nutrition. While summarizing the activities of pectin-degrading enzymes, their industrial applications, and gene sources, this review projects another application for pectinases, which is the use of enzymatically derived pectin moieties in functional food preparation.
A cell-wall-surface protein purified from the cells of Saccharomyces cerevisiae NCYC 227 was found to be involved in the non-sexual flocculation of this yeast. This 13 kDa protein was found to bind specifically to mannose. The protein bound to mannans isolated from yeast as well as in situ to intact cells, but only in the presence of calcium ions. The protein, a mannoprotein, formed aggregates as revealed in SDS-PAGE. Urea and higher temperatures prevented protein aggregation, suggesting that the flocculation of S. cerevisiae is primarily due to hydrogen bonding between mannan and protein.
A 125-kDa starch hydrolysing enzyme of Aspergillus niger characterised by its ability to dextrinise and saccharify starch [Suresh et al. (1999) Appl. Microbiol. Biotechnol. 51, 673^675] was also found to possess activity towards raw starch. Segregation of these activities in the 71-kDa glucoamylase and a 53-kDa K K-amylase-like enzyme supported by antibody crossreactivity studies and the isolation of mutants based on assay screens for the secretion of particular enzyme forms revealed the 125-kDa starch hydrolysing enzyme as their precursor. Nterminal sequence analysis further revealed that the 71-kDa glucoamylase was the N-terminal product of the precursor enzyme. Immunological cross reactivity of the 53-kDa amylase with antibodies raised against the precursor enzyme but not with the 71-and 61-kDa glucoamylase antibodies suggested that this enzyme activity is represented by the C-terminal fragment of the precursor. The N-terminal sequence of the 53-kDa protein showed similarity to the reported Taka amylase of Aspergillus oryzae. Antibody cross-reactivity to a 10-kDa non-enzymic peptide and a 61-kDa glucoamylase described these proteins as products of the 71-kDa glucoamylase. Identification of only the precursor starch hydrolysing enzyme in the protein extracts of fungal protoplasts suggested proteolytic processing in the cellular periplasmic space as the cause for the secretion of multiple forms of amylases by A. niger.z 2000 Federation of European Biochemical Societies.
Aim: Characterization of dehydromonacolin‐MV2, a bioactive metabolite isolated from Monascus purpureus mutant (CFR 410‐11).
Methods and Results: Chloroform extract of rice, fermented with a hyperpigment‐producing mutant of M. purpureus (CFR 410‐11) was found to contain metabolites that inhibited the growth of Bacillus, Pseudomonas and Streptococcus in agar gel diffusion assays. The extract inhibited lipid peroxidation and scavenged 2,2‐diphenyl‐1‐pycrylhydrazyl and hydroxyl radicals. The active compound purified by silica gel column chromatography was characterized by NMR. The carbon, proton and 2D HSQCT assignments identified dehydromonacolin‐MV2 as the bioactive metabolite.
Conclusions: Dehydromonacolin‐MV2 apparently originated in the mutant by hydroxylation and oxidation of monacolin‐J, an intermediate of monacolin biosynthetic pathway.
Significance and Impact of the Study: Identification of the production of dehydromonacolin‐MV2 by M. purpureus mutant (CFR 410‐11) is new to literature. Bioactive properties of the compound suggested its pharmaceutical applications.
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