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278 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGY1. INTRODUCTIONVitamin K, a group of fat-soluble vitamins with a shared chemical structure of 2-methyl-1,4-naphthoquinone, plays a crucial role in human health by participating in blood coagulation and regulating bone metabolism. Vitamin K1 contains a partially unsaturated side chain, composed of one isopentenyl unit followed by three isopentyl units, whereas vitamin K2, referred to as menaquinones (MK-n), has a fully unsaturated side chain comprising 2%u201313 isopentenyl units (where n indicates the number of isopentenyl units). Vitamin K1, which is abundant in dark green leafy vegetables, represents the primary form of vitamin K in the daily diet; however, less than 10% of dietary vitamin K1 is absorbed in the digestive tract [1]. Vitamin K2, primarily synthesized by bacteria, is also present in meats, eggs, and is especially concentrated in fermented foods such as cheese and natto.In humans, both vitamins K1 and K2 act as essential cofactors for the enzyme gamma-glutamyl carboxylase, a function facilitated by their common naphthoquinone ring structure. This enzyme is involved in the carboxylation of vitamin K-dependent proteins, including matrix Gla protein (an inhibitor of vascular calcification), osteocalcin (which transports Ca2+ ions into the bone matrix), and various proteins involved in blood coagulation [2]. Due to structural differences, vitamin K2 is believed to exhibit higher bioavailability and absorption rates, a longer half-life, and broader extrahepatic activity compared to vitamin K1 [3]. Recent studies have also demonstrated that vitamin K2 inhibits the growth of liver cancer cell lines, protects neurons from %u03b2-amyloid peptide toxicity-a factor contributing to Alzheimer%u2019s disease-and activates proteins Gas6 (growth arrestspecific gene 6) and protein S, which are involved in cognitive processes in the brain [4,5]. Vitamin K2 has been recognized