17 S. Mahboob S. Haider S. Sultana K. A. Al- Ghanim F. Al-Misned H. F. Al-Kahem Al-Balawi Z. Ahmad Journal of Animal and Plant Sciences JAPS 20142014/12/01 24 6 1802-1810 1018-7081 NA <p>The study was designed to isolate and characterize the collagen from skin, scales and fins of&nbsp;<em>Cyprinus carpio</em>&nbsp;and&nbsp;<em>Hypophthalmichthys molitrix</em>. For this purpose nine fishes of each species of three weight groups were collected and categorized as W1 (250-500 g), W2 (501-750 g) and W3 (751- 1000 g). The maximum skin protein content was recorded as 28.13% and 29.13% in&nbsp;<em>C. carpio&nbsp;</em>and&nbsp;<em>H. molitrix</em>, respectively, from the W3. The scales of the W3&nbsp;displayed a maximum protein contents as 29.91 and 28.38% for&nbsp;<em>C. carpio&nbsp;</em>and&nbsp;<em>H. molitrix,&nbsp;</em>respectively. The maximum protein contents (19.19% and 21.37% for&nbsp;<em>C. carpio&nbsp;</em>and&nbsp;<em>H. molitrix,&nbsp;</em>respectively) were observed in the W3&nbsp;group. Protein characterisation using SDS-PAGE revealed the molecular weights (kDa) of the&nbsp;<em>C. carpio&nbsp;</em>skin, scales, and fins ranged from 126 kDa to 220 kDa, 78 kDa to 211 kDa, and 72 kDa to 141 kDa, respectively. The size of the collagen proteins of the&nbsp;<em>H. molitrix&nbsp;</em>skin, scales and fins ranged from 117 kDa to 208 kDa, 81 kDa to 219 kDa, and 72 kDa to 141 kDa, respectively. Glycine was the most abundant amino acid, whereas, Tryptophan was totally absent in all selected tissues. Significant differences were observed for amino acids within the weight groups and between the two fish species.</p> Fish; Proximate composition; weight groups; Amino acids; SDS-PAGE Pakistan Agricultural Scientists Forum https://thejaps.org.pk/AbstractView.aspx?mid=2014-JAPS-258