THE DESTRUCTION OF SERINE AND THREONINE DURING ACID HYDROLYSIS

Bovine submaxillary mucin (a glycoprotein) was hydrolyzed for varous times (1 to 300 hr) at 110° in 6 N HCl (0.3 mg protein per ml). The kinetics of destruction of serine were found to be first‐order and that of threonine to be zero‐order. The velocity constant for the destruction of serine was k – 4.3 X 10‐ 3 hr‐ 1 and of threonine was k – 5.6 X 10‐ 4 mole hr 1 . The amounts of serine and threonine destroyed after 22 hours hydrolysis were 10.0 % and 2.7 %, respectively. Since the losses were the same in the absence of carbohydrates and since several prior extensive investigations reported similar corrections for serine, these corrections may be applicable to most proteins and glycoproteins.