| Summary: | 碩士 === 國立彰化師範大學 === 生物學系 === 100 === Sco-CHH and Sco-CHH-L (CHH-like peptide), two structural variants of the crustacean hyperglycemic hormone family identified in the mud crab ( Scylla olivacea ), are presumably alternatively spliced gene products. In this study, mutants of rSco-CHH-Gly was α-amidated at the C-terminal end to produce mutated rSco-CHH (I2G、F3A、D12N、R13A、Q51A、E54Q), the identities of which were confirmed by mass spectrometric analyses. In bioassays, the hyperglycemic activity of I2G (The second amino acid of mature Sco-CHH isoleucine mutated to glycine) decreased by 38.7 %, F3A (phenylalanine mutated to alanine) decreased by 37.7 %, D12N (phenylalanine mutated to alanine) decreased by 52.9 %. The substitutions of critical residues at the N-terminus maybe affect the stability of Sco-CHH. Q51A (glutamine mutated to alanine) decreased by 20.8 % and E54Q (glutamic acid mutated to glutamine) decreased by 28.7 %. Result of bioassays indicated that two mutants have slightly effect on hyperglycemic activity. In physiological function analysis, the 1.25 × 102 ~ 1.25 × 104 pM of rSco-CHH-L increased the Na+/K +-ATPase activity in gill, midgut and hindgut, whereas rSco-CHH did not. According to function analysis indicated that the two CHH structural variants have divergent function.
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