Masashi Akiyama

Molecular cloning and expression of human caldecrin

Earlier we reported the primary structure of serum calcium‐decreasing factor (caldecrin) from rat pancreas, a protein which is considered to be a member of the elastase family. In this report, we describe the isolation of the two homologous cDNA clones encoding caldecrin from human pancreas, the structures of which are identical except for one base and the corresponding amino acid residue. These human caldecrin isoforms are composed of a signal peptide of 16 amino acids, a propeptide of 13 amino acids, and a mature form of 239 amino acids. Both recombinant caldecrins showed the same chymotrypsin‐type protease activity and hypocalcemic activity. The hypocalcemic activity of both remained intact even after treatment with PMSF to abolish their protease activity. These results suggest that human caldecrin possesses hypocalcemic activity that has no connection with its protease activity.

Total synthesis of (±)- and (+)-latifine

Racemic latifine (+)-(1), a new representative of the rare phenolic Amaryllidaceae alkaloids, has been synthesized by employing the Claisen rearrangement of 4-benzyloxycinnamyl 2-methoxyphenyl ether (11) as a key step. Based on the racemic synthesis, (R)-(+)-latifine (R)-(1), the unnatural enantiomer, has also been synthesized from (S)-O-benzylglycidol (S)-(3)via(S)-1-benzyloxy-3-phenylthio-propan-2-ol (S)-(4) as a key intermediate.