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Boron Trifluoride‐Etherate (Lewis Acid) as an Efficient Acid at Cyclization/Cleavage Reaction of D / L ‐Amino Acids Affording the Retention of their Original Configuration in the Edman Sequencing Method of Peptides
Author(s) -
Matsunaga Hirokazu,
Iida Takayuki,
Fukushima Takeshi,
Santa Tomofumi,
Homma Hiroshi,
Imai Kazuhiro
Publication year - 1996
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/(sici)1099-0801(199603)10:2<95::aid-bmc557>3.0.co;2-h
Subject(s) - chemistry , boron trifluoride , edman degradation , cleavage (geology) , chromatography , lewis acids and bases , amino acid , organic chemistry , peptide sequence , biochemistry , catalysis , geotechnical engineering , fracture (geology) , engineering , gene
Boron trifluoride‐etherate (BF 3 ), one of the Lewis acids, was found to be an efficient acid in the Edman sequencing method, affording the retention of the N ‐terminal amino acid configuration at the cyclization/cleavage reaction from peptides. Examples for the sequencing of D ‐Leu‐Gly and L ‐Pro‐ L ‐Leu are described, utilizing 7‐ N , N ‐dimethylaminosulphonyl‐4‐(2,1,3‐benzoxadiazolyl) isothiocyanate (DBD‐NCS) as a fluorogenic Edman reagent. The peptide labelled with DBD‐NCS was cyclized/cleaved with 1% BF 3 in dichloroethane containing 0.02% ethanethiol at 50°C for 5 min. The resultant DBD‐thiazolinone (TZ)‐amino acid was separated on a phenylcarbamoylated cyclodextrin column with fluorometric detection at 524 nm with excitation at 387 nm. DBD‐TZ‐amino acids thus obtained showed remarkable retention of their configuration of α‐carbon atoms of amino acids (DBD‐TZ‐ L ‐Leu; 3%, ‐ D ‐Pro; 6%). Even after 30 min of the cyclization/cleavage reaction at 50°C, DBD‐TZ‐amino acids retained their configuration to the same degree. On the other hand, DBD‐TZ‐amino acid obtained by cyclization/cleavage reaction with TFA at 50°C for 5 min was racemized to a great extent (DBD‐TZ‐ L ‐Leu; 31%, ‐ D ‐Pro; 48%). BF 3 should be the most recommendable acid at the cyclization/cleavage reaction for amino acid sequence and configuration determination of peptides containing D ‐amino acid residues.