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A purified glycoprotein with blood-group-A specificity, was digested with insoluble pronase to give a serologically active product enriched in peptide-bonded serine and threonine residues; this was degraded with 0.25 M sulphuric in glacial acetic acid for 24 h. The resultant N-acetylgalactosaminyl-peptide were hydrolysed with 0.2 M hydrocholoric acid for 24 h at 110 °C. fractionation of the products on Sephadex G-10, followed by preparative separation on amino-acid analyzer and paper electrophoresis at pH 1.9 yielded the following homogeneous oligopeptides; one tripeptide with the N-terminal sequence Thr-Thr-Ser, three tetrapeptides with the sequences, Thr-Ser-Thr-Ser, Thr-Pro-Thr-Ser and Pro-Thr-Thr-Ser, one pentapeptide with the sequence Thr-Pro-Thr-Ser, one hexapeptide with the sequence Pro-Thr-Thr-Thr-Pro-Ser and one heptapeptide with the sequence Ala-Pro-Thr-Thr-Ser-Gly-Ser. Galactosamine was present in several of these fragments and the hexapeptide and heptapeptide both contained sufficient of this sugar for all the serine and threonine residues to be glycosylated. The following five tetrapeptides sequences were deduced from mixtures of two peptides which differed by the amino-acid substituent at only one position in the chain; Pro-Thr-Ala-ser, Thr-Thr Pro-Ser, thr-Thr-Ala-Ser, Ser-Pro-Thr-Ser, and Ser-Ala-Thr-Ser. A tripeptide mixture which differed only in the nature of the third amino acid yielded the following three tripeptide sequences: Pro-Thr-Ser, Pro-thr-Ala. These peptides do not indicate a clearly defined amino-acid sequence surrounding the glycosylated hydroxy amino acids but establish that in the human blood-group-specific glycoproteins there is close packing of the threonine in the region of the peptide moiety carrying the carbohydrate chains. [ABSTRACT FROM AUTHOR]

The globin of sheep heart myoglobin was first cleaved by cyanogen bromide and the resulting fragments were fractionated by gel filtration and preparative paper electrochromatography; each fragment was submitted to endopeptidase digestion and the complete amino acid sequence has been determined. The intact globin and the median cyanogen bromide peptide were analysed by the protein sequanator (Edman). This analysis confirmed the sequence of the first 46 N- terminal residues of the intact globin and established the sequence of the first 39 N-terminal residues of the median cyanogen bromide peptide. Between sheep and beef myoglobin six differences over 153 residues can be noticed; among the six amino acid replacements, two correspond to the exchange of two bases and four to the exchange of one base in the coding triplets. [ABSTRACT FROM AUTHOR]