Enzymatic processes after slaughter:
1.  autolytic process: cathepsins and other enzymes of hide itself are involved.
2.  deterioration process: proteolytic activity of bacterial enzymes.
3.  processes intentionally carried with enzymatic preparations like soaking  and unhairing
4.  bating: enzymes attack on proteins remaining in the collagen "wove" after all the beamhouse operations have been done.

Most important enzymes involved in leather making are the proteolytic enzymes.

Proteolytic enzymes: peptidases and proteinases (peptide hydrolases)
Pepsin : active at low pH (formed in stomach mucosa) cleaves gelatin
renin : almost the same activity
Trypsin :  (formed in intestine) most stable at pH ~3.
Chymotripsin : (formed in pancreas) most active at pH 8.
Cathepsin :  intercellular enzymes pH 3.7 - 4.
Papain (from papaya) : optimum pH 5.5-6 ; but active in temperature 5-66 ⁰C from  pH 2.8 to 10.8. Very broad.
Elastase  : (formed in pancreas) pH 8.8  optimum activity 
Collagenases :  bacterial collagenases, animal collagenases ; attack collagen in its helical part. pH 8-9
Lipases : (hydrolyze fatty acid esters) attack ester bonds.