Amino Acid Composition of Egg Proteins

C-TERMINAL RESIDUES IN PROTEINS 111 residues in proteins, the need for which was emphasized in the introduction, is still unsolved and remains a challenge to the analyst. SUMMARY 1. The carboxyl groups of C-terminal residues in proteins, after preliminary esterification, can be reduced with lithium borohydride, and on subsequent acid hydrolysis the modified residues are present in the hydrolysate as amino alcohols or hydroxyamino acids as the case may be.2. The suitability of the procedure for determining the C-terminal residues in proteins has been explored, and in agreement with Crawhall & Elliott (1955), it was found that the issue was complicated by the simultaneous reductive cleavage of peptide bonds which occurs, under the conditions chosen, to the extent of 1-2 % of the total peptide bonds.3. Data are presented showing that with a protein of low molecular weight such as insulin (5732) the interference is not serious and a satisfactory determination of the C-terminal residues can be made. With a protein of much higher molecular weight such as P-lactoglobulin (37 000), however, the interference is serious.4. The procedure is not recommended as a reliable one for proteins but it may be of use with peptides of low molecular weight.One of us (A. C. C.) would like to acknowledge the generous financial assistance provided by Eli Lilly and Co., Indianapolis, U.S.A.

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“…14 700). The amide N given in Table 1 is in agreement with that of Lewis, Snell, Hirschmann & Fraenkel-Conrat (1950). SUMMARY 1.…”

Section: Resultssupporting

confidence: 83%

Studies on the amide and C-terminal residues in proteins. 2. The ammonia nitrogen and amide nitrogen of various native protein preparations

Chibnall

Mangan

Rees

1958

Biochemical Journal

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“…The molar tyrosinetryptophan ratio has been reported to be 3 to 8 (18), 3 to 7 (10), and 3 to 6 (8, 17) as determined by chemical and microbiological methods.…”

Section: Methodsmentioning

confidence: 99%

Determination of Tyrosine and Tryptophan in Proteins

Bencze¹,

Schmid²

1957

Anal. Chem.

765

207

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“…That there are differences in tryptophan content in several of the gramicidin fractions is indicated by all the analyses, and the differing yields of ammonia (Table II), which presumably arise from the decomposition of tryptophan, seem to reflect this variation. Reported literature values for the tryptophan content of unfractionated gramicidin fall in the range 39.3-45% (Edwards, 1949;Lewis et al, 1950; Ramachandran and Witkop, 1959), and gramicidin A and gramicidin B are reported as containing four moles of tryptophan per mole of glycine (Stein and Moore, 1949-50;Ishii et al, 1962). A final statement on the actual tryptophan content of the different gramicidins would be made possible by direct identification of the different tryptophanyl sequences in each molecule during structural investigations.…”

Section: Discussionmentioning

confidence: 99%

On the Heterogeneity of Gramicidin

Ramachandran¹

1963

Biochemistry

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Amino Acid Composition of Egg Proteins

Cited by 184 publications

References 24 publications

Studies on the amide and C-terminal residues in proteins. 2. The ammonia nitrogen and amide nitrogen of various native protein preparations

Studies on the amide and C-terminal residues in proteins. 2. The ammonia nitrogen and amide nitrogen of various native protein preparations

Determination of Tyrosine and Tryptophan in Proteins

On the Heterogeneity of Gramicidin

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