title: An improved procedure for automated Edman degradation used for determination of the N-terminal amino acid sequence of human transcobalamin I and human intrinsic factor.
abstract: An improved procedure for automated Edman degradation is presented. Three programs are described, one with double cleavage and two with single cleavage. The programs presented are characterized by a reversed delivery scheme for buffer and phenyl isothiocyanate, and by reduced cleavage times. The modified procedures applied on automated Edman degradation of the vitamin B12-binding proteins human transcobalamin I and human intrinsic factor, containing approximately 390 and 350 amino residues respectively, gave the following N-terminal amino acid sequences: Human transcobalamin I Glu-Ile-Cys-Glu-Val-Ser-Glu-Glu-Asn-Tyr-Ile-Arg-Leu-Lys-Pro-Leu-Leu-Asn-Thr-Met-Ile-Gln-Ser-Asn-Tyr-Asn-?-Gly- Human intrinsic factor Ser-Thr-Gln-Thr-Gln-Ser-Ser-Cys-Ser-Val-Pro-Ser-Ala-Gln-Glu-Pro-Leu-Val-Asn-Gly-Ile-Gln-?-Leu-Met-Glu-Thr- The background accumulation seems to be related not only to the length of the polypeptide chain being degraded, but also to the content of serine (and possibly threonine). A possible N leads to O acyl shift during the cleavage is a tentative explanation. The programs here represented lead to a significant reduction in background compared to conventional programs and allowed considerable prolongation of the degradations.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001322:Autoanalysis / Q000379:methods; D001798:Blood Proteins / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D005750:Gastric Juice / Q000032:analysis; D006801:Humans; D007437:Intrinsic Factor; D008113:Liver Neoplasms / Q000378:metabolism; D014155:Transcobalamins / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001798:Blood Proteins; D014155:Transcobalamins; D007437:Intrinsic Factor