Primary Structure and Enzymatic Properties of Chitinase Isozymes Purified from the Stomach of the Marbled Rockfish Sebastiscus marmoratus
We purified three chitinase isozymes, SmChiA, SmChiB, and SmChiC from the stomach of the marbled rockfish Sebastiscus marmoratus by ammonium sulfate fractionation and column chromatographies. The molecular masses of SmChiA, SmChiB, and SmChiC were estimated to be 46, 52, and 56 kDa
by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. These chitinases showed the optimum pH toward both short and long substrates in the acidic region (pH 2.0–4.5). SmChiA and SmChiB preferentially degrade the second glycosidic bond from the non-reducing end of
N-acetylchitooligosaccharides ((GlcNAc) n ) and SmChiC preferentially degrades the third glycosidic bond. These chitinases exhibited wide substrate specificities toward crystalline chitin. Moreover, two cDNAs, SmChi-1 encoding SmChiA and SmChiB, and SmChi-2 encoding SmChiC were cloned.
The homology between the deduced amino acid sequences of SmChi-1 and SmChi-2 was 85.5%. The deduced amino acid sequences of both chitinases showed similarity to those of previously reported fish chitinases. In a phylogenetic tree analysis, SmChi-1 and SmChi-2 were classified into fish-specific
acidic fish chitinase-1 (AFCase-1) and acidic fish chitinase-2 (AFCase-2), respectively. Our results strongly support that fish have a chitin-degrading enzymatic system that efficiently degrades chitin ingested as food, in which two different chitinases (AFCase-1 and AFCase-2) with different
degradation patterns are expressed in the stomach. The results also suggest that S. marmoratus produces a chitinase in its stomach which has high specific activity by processing the C-terminal sequence to efficiently degrade chitin ingested as food.
Keywords: CHITINASE ISOZYMES; FISH STOMACH; FISH-SPECIFIC ACIDIC FISH CHITINASE; SEBASTISCUS MARMORATUS; SUBSTRATE SPECIFICITY
Document Type: Research Article
Publication date: 01 June 2014
- Journal of Chitin and Chitosan Science (JCC) is an international peer-reviewed journal that covers all aspects of chitin and chitosan based biomaterials and their derivatives, their sources, commercial production, processing, spectroscopic characterization, biochemistry, biology, enzymology, ecology, chemical and physico-chemical properties, biological activities, medical and biomedical applications such as drug delivery systems, gene delivery, pharmaceuticals, tissue engineering, wound healing agents, antimicrobial activities, biotextiles, biocatalysis, food science, agriculture, water purification, environment, and other areas of life sciences and materials science.
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