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1H n.m.r. studies of Z-Thr-OMe, Z-Thr-Ala-OMe, Z-Ala-Thr-OMe and their glycosylated derivatives indicate the possibility of an intramolecular hydrogen bond between Thr N alpha H and the N-acetyl carbonyl of the carbohydrate moiety, 3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-alpha-D-galactopyranose (AcGalNAc). This is especially true in the case of Z-Thr(AcGalNAc)-Ala-OMe, suggesting that the strength of this hydrogen bond is dependent on the neighboring amino acids on the carbonyl terminal side of Thr. The existence of such a hydrogen bond implies a conformation in which the carbohydrate moiety is restricted to an orientation with its plane roughly perpendicular to the peptide backbone. In such an orientation, steric problems will be minimized in the case of clustered O-glycosidically linked Thr(Ser) residues as found in human erythrocyte glycophorin. A locked orientation of the carbohydrate moiety with respect to the peptide backbone may also play a conformational role in antifreeze glycoproteins.

Pterygium is a kind of degenerative lesion of the ocular conjunctiva and is thought to be hyperaemia of fibrovascular tissue onto the cornea caused by various factors. The most frequently used treatment for pterygium at present is surgery. Various surgical procedures and postoperative treatments for pterygium have been reported, however, the postoperative recurrence rates are somewhat high. Therefore, until now we have had no satisfactory clinical management of pterygium. The results of our method for surgical treatment of pterygium are given and compared with those described in many other reports. From this comparison, our clinical surgical treatment of pterygium, which is the so-called "bare sclera" technique, is evaluated to give the best management without serious complications and recurrences.