. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PROPERTIES OF THE BIVALVE LIGAMENT 171 carbonate, or the X-ray analysis was not sufficiently sensitive to detect the crystalline phase. Ligament tissue, like many structural proteins such as elastin, resilin, keratin, and collagen (old), are found in a solid phase which is relatively insoluble. The results of the amino acid analysis are shown in Table II. The outer ligaments were not considered; however, the outer ligament of Spisnla solidissnna was included for comparative purposes, as was the shell protein from Crassostrea
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PROPERTIES OF THE BIVALVE LIGAMENT 171 carbonate, or the X-ray analysis was not sufficiently sensitive to detect the crystalline phase. Ligament tissue, like many structural proteins such as elastin, resilin, keratin, and collagen (old), are found in a solid phase which is relatively insoluble. The results of the amino acid analysis are shown in Table II. The outer ligaments were not considered; however, the outer ligament of Spisnla solidissnna was included for comparative purposes, as was the shell protein from Crassostrea znrginica. The most striking feature of these analyses is the concentration of glycine found in the ligaments of the eight species of bivalves examined. Over 500 glycine residues per thousand total residues were measured in the ligament hydrolyzates of four of the eight species examined. Only C. rirginica had fewer than 200 glycine residues per thousand, while the presence of nearly 70% glycyl residues occurred in A. ir- radians and P. vnagellanicus hinge ligament protein. Among the ligaments ex- amined, C. virginlca had the highest concentration of alanine (9%). A significant difference between ligament protein and many other structural proteins is the presence of the sulfur-containing amino acids, methionine and cystine/2. The presence of cystine/2 residues may be indicative of the degree of cross-linking in the ligament protein. It is obviously important that the cross-links be relatively few and widely spaced so that stretching may occur without rupture of strong bonds. Some cross-linking is necessary, however, to prevent the slipping of one chain past another (Weis-Fogh, 1961; Partridge, 1962), yet a considerable degree of cross-linking may be possible without impairing mechanical function. The ex- ternal ligaments of Mercenaria and Ensis are subject to stretching during valve adduction. Covalent cross-linking would probably not be incompatible with this functional morpho
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
