Investigating the molecular building blocks of loose and tight cattle hide : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Biochemistry at Massey University, Manawatu, New Zealand

Abstract

Looseness is a defect found in 7% of leather made from cattle hides. It affects the quality of leather, resulting in the leather being downgraded or potentially being discarded altogether. The similarity in appearance between loose leather and wrinkly skin led to the hypothesis that they may share the same causative agent(s). While little to no research has been done to elucidate the molecular basis of loose leather, there are many reports detailing the characteristics and causes of wrinkly skin, especially in ageing humans. Studies have shown that changes in three molecular components of skin are correlated with the appearance of wrinkles; collagen, elastin and glycosaminoglycan’s (GAGs). Cattle hides that produce loose leather were identified by processing half of the selected hides to leather and using the SATRA break scale. Only four hides were suitable for this study with two being loose and two being tight. Although this small sample size limited the statistical significance of the results, it did, however, enable a vast number of analyses on the molecular components of the hides to be carried out. Microscopic techniques were utilised to investigate the localisation and structure of a range of molecular components in loose and tight hides and a series of biochemical assays were used to assess the carbohydrate components, particularly the GAGs. Quantitation of amino acids in the whole hide and different layers of the hide; grain, grain to corium junction and corium provided insight into the total collagen found in loose and tight hides and proteomic analysis using in-gel mass spectrometry (in-gel LC-MS/MS) enabled quantitation of all soluble proteins found in loose and tight hides as well as the extent of collagen glycosylation. Overall loose hides appear to have a decrease in fibrillar collagen, this paired with changes in total crosslinks and glycosylation of collagen potentially result in changes to the structure and organisation of the collagen network. This causes easier extraction of non-collagenous components during leather processing and thus results in loose leather. This study uses a variety of techniques to link differences in the molecular components of hide to the defect looseness. This greater understanding of how the molecular components of raw hide can affect the quality of leather will be of use in developing methods to identify faults in the hide before it is processed to leather and developing methods to produce high quality leather.