Jae-Hyeung Pyeun

Enzymatic properties of anionic trypsins from the hepatopancreas of crayfish, Procambarus clarkii☆

Abstract Maximum amidolytic and esterolytic activities of crayfish hepatopancreatic trypsins occurred in a pH range of 7.5–8.5. Activity of trypsin A increased by addition of 0.5 mM of Ca 2+ ions; however, other trypsins were not affected by this concentration. Kinetic properties of crayfish trypsins toward esterolytic reaction were similar, but those for amidolytic reaction were different. Activation energies for esterolytic reaction were approximately 6.4–9.0 kcal/mole, while those for amidolytic reaction were between 5.9 and 6.9 kcal/mole.

Changes of Food Compopents in Mesangi (Capsosiphon fulvecense), Gashiparae (Enteromorpha prolifera), and Cheonggak (Codium fragile) Depending on Harvest Times

The change of food components in seaweeds, masangi (Capsosiphon fulvecense), gashiparae (Enteromorpha prolifera) and cheonggak (Codium fragile) was investigated at various harvest times. The crude protein was for masangi and for gashiparae, respectively. The content of glutamic acid, aspartic acid and leucine among total amino acid was high. The major free amino acids were proline and alanine for masangi, asparagine and glutamic acid for gashipare, and hdyrolxyproline, glutamic acid and alanine for cheonggak. In gashipare, the content of aspargine was greatly decreased, while one of sarcosine was increased in March. The ratio of polyene was for masangi, for gashipare, and for cheonggak. The levels of Ca, K, Mg and Fe were high. In masangi and gashiparae, the chlorophyll a and b was greatly decreased in March.

Properties of proteases responsible for degradation of muscle proteins during anchovy sauce fermentation

The protease playing an important role in anchovy sauce fermentation was attempted to isolate, and properties of the three proteases such as trypsin, chymotrypsin and cathepsin L-like enzyme purified from anchovy, Engraulis japonica, were investigated. The molecular weights of trypsin, chymotrypsin and cathepsin L-like enzyme purified from anchovy viscera and muscle were estimated by SDS-PAGE to be 25.6 kDa, 26.1 kDa and 25.8 kDa, respectively. The trypsin and chymotrypsin had their maximal activity at pH 8.0 and 45°C for synthetic substrates, while cathepsin L-like enzyme showed maximal activity at pH 6.0 and 50°C for N-benzoyl-D,L-arginine-β-naphthylamide. Trypsin, chymotrypsin and cathepsin L-like enzyme had higher Km values for myofibrillar proteins than those for casein. The kcat of chymotrypsin and cathepsin L-like enzyme for myofibrillar proteins were higher than that of trypsin, and also chymotrypsin and cathepsin L-like enzyme caused higher hydrolysis in myofibrillar proteins of anchovy. Proteolytic activities were decreased with increase in sodium chloride concentration. Cathepsin L-like enzyme and chymotrypsin were more responsible for the autolysis of muscle proteins from fish and fermentation during fish sauce processing than trypsin.