Hydroxyproline identification

Yamaguchi et al. also showed that Rb-L-prolinate catalyzes enantioselective addition of nitroalkanes to several acyclic and cyclic enones [25, 26]. For acyclic enone acceptors the best result, i.e. 74% yield and 68% ee of the S product, was achieved in the addition of 2-nitropropane to -3-penten-2-one (40a, Scheme 4.13) [25]. Screening of several proline derivatives and cyclic amino acids of other ring size resulted in the identification of the O-TBDMS-derivative of 4-hydroxyproline as the best catalyst for addition of nitrocyclohexane to cycloheptenone. In this particular reaction 74% yield and 86% ee were achieved [26]. 

Identification Pork Collagen contains not less than 5.52% hydroxyproline, corresponding to 40.0% collagen, as determined under Assay (below). 

Modified or unusual amino acids such as hydroxyproline and phos-phoserine and protected amino acids can also be identified by Edman degradation sequence analysis [38], However, it is important to remember that in this method, identification of a residue is made solely on the basis of HPLC retention time. It is, therefore, essential to support the identification of a modified residue by comparison with authentic standards. Furthermore,... 

Single galactosyl residues are glycosidically attached to the serine hydroxyls of the hydroxyproline-rich cell wall proteins of suspension-cultured tomato cells (84, 85). This was shown by removing the arabinosides from the intact cell walls by acid hydrolysis (pH 1 for 1 hr at 100° C). The hydroxyproline-rich wall protein, with arabinosyl residues removed, is susceptible to proteolysis with trypsin. The resulting solubilized tryptides have been separated by cation exchange and gel filtration chromatography. The composition of the tryptides has been determined by amino acid analysis (85). Some of the tryptides have been sequenced by subtractive N-terminus identification and further partial acid hydrolysis (85). 

---