Enzymatic Baiting Technology for Wet Blue: I. Characterization of Protease Activities Towards Chrome-tanned Elastin and Collagen Fibers

Abstract

To characterize the reacting performances of proteases againstchrome-tanned leather, the methods to quantitatively measureprotease activities against chrome-tanned elastin and collagenfibers were established through detecting the produced amountof Desmosine (DES) or Hydroxyproline (Hypro) in unit time.Chrome-tanned elastin and collagen fiber substrates withdifferent Cr content were prepared, and the influence of the Crcontent on the enzymatic hydrolysis resistance of tannedsubstrates was investigated. The activities of several typicalproteases against chrome-tanned elastin and collagen fiberswere tested based on the methods, and the relationship betweenthe activities and bating effectiveness on wet blue was alsopreliminarily investigated. The results showed that the two kindsof activities of proteases decreased with the increase of Crcontent in the substrates. When the Cr contents in elastin orcollagen fiber reached 0.5% or 2.0%, the corresponding activityapproached to the lowest level, respectively. Different proteaseshowed different activity decrease extend towards tannedprotein fibers. Meanwhile, the bating effectiveness of proteaseson wet blue was positively related to their activities towards thechrome-tanned protein fibers measured by the establishedmethods, i.e. proteases with highly chrome-tanned elastin andcollagen fiber activities could significantly improve the softnessof leather. The new methods can be used as an available tool tocorrectly select proteases and optimize process parameters forwet blue bating.