Hokkaido University · Biochemistry, Genetics and Molecular Biology
Professor Hideki Kishimura's research lab specializes in marine bioresources, focusing on the isolation, characterization, and functional evaluation of bioactive peptides and natural compounds from marine algae and fish. The lab investigates enzyme activities in marine organisms, particularly proteases like pepsin and trypsin, and explores their applications in food and health sciences. A key research direction involves the extraction and analysis of mycosporine-like amino acids (MAAs) from red algae such as dulse, emphasizing their UV-protective and antioxidant properties for potential use in cosmetics and nutraceuticals. The lab also studies protein hydrolysates for ACE-inhibitory peptides with antihypertensive potential, contributing to functional food development.
Figures are computed from collected data and may differ slightly.
We examined the inhibitory activity of angiotensin I converting enzyme (ACE) in protein hydrolysates from dulse, Palmaria palmata. The proteins extracted from dulse were mainly composed of phycoerythrin (PE) followed by phycocyanin (PC) and allophycocyanin (APC). The dulse proteins showed slight ACE inhibitory activity, whereas the inhibitory activity was extremely enhanced by thermolysin hydrolysis. The ACE inhibitory activity of hydrolysates was hardly affected by additional pepsin, trypsin an
Pepsin from the stomach of albacore tuna, skipjack tuna, and tongol tuna was characterized. Pepsin from all tuna species showed maximal activity at pH 2.0 and 50 degrees C when hemoglobin was used as a substrate. Among the stomach extract of all species tested, that of albacore tuna showed the highest activity (40.55 units/g tissue) (P < 0.05). Substrate-Native-PAGE revealed that pepsin from albacore tuna and tongol tuna consisted of 2 isoforms, whereas pepsin from skipjack tuna had only 1 form.
Two isozymes of trypsin (TR-I and TR-II) were purified from the viscera of Japanese anchovy (Engraulis japonica) by gel filtration and anion-exchange chromatography. Final enzyme preparations were nearly homogeneous in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the molecular weights of both enzymes were estimated to be 24,000 Da by SDS-PAGE. The N-terminal amino acid sequences of the TR-I, IVGGYECQAHSQPHTVSLNS, and TR-II, IVGGYECQPYSQPHQVSLDS, were found. Both TR-I
Mycosporine-like amino acids (MAAs) are the ultraviolet (UV)-absorbable compounds, which are naturally produced by cyanobacteria and algae. Not only these algae but also marine organisms utilize MAAs to protect their DNA from UV-induced damage. On the other hand, the content of MAAs in algae was changed by the environmental condition and season. In addition to the UV-protected function, the antioxidant capacity of MAAs can apply to the cosmetic sunscreen materials and anti-cancer for human healt
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