  1.4.99.B4 | analysis |
estimation of the content of L-hydroxyprolines using coupling systems with metabolic enzymes of the trans-4-hydroxy-L-proline pathway (hydroxyproline 2-epimerase (HypE) and cis-4-hydroxy-D-proline dehydrogenase (HypDH)) and the trans-3-hydroxy-L-proline pathway (trans-3-hydroxy-L-proline dehydratase (T3LHypD) and DELTA1-pyrroline-2-carboxylate reductase (Pyr2CR)) from microorganisms. A functional expression system of recombinant HypDH with a heterooligomeric structure is constructed in Escherichia coli cells. Enzymological characterization reveals that the beta-subunit acts as a catalytic subunit, and also that assembly with other subunit(s) improves the kinetics for cis-4-hydroxy-D-proline and thermostability. By using a spectrophotometric assay with different wavelengths, the contents of trans-4-hydroxy-L-proline and trans-3-hydroxy-L-proline are successfully estimated within the ranges of 0.004-1 mM and 0.05-1 mM, respectively, and are consistent with the contents determined by HPLC. This enzymatic method is used to measure the content of trans-4-hydroxy-L-proline in the acid-hydrolysate of collagen, and blood plasma |
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