5 p-CHOLESTANE · 3 a , 27-DIOL : NAD + OXIDOREDUCTASE AND 3 a-HYDROXY-5 p-CHOLESTAN-27-AL : NAD + OXIDOREDUCT ASE IN RAT LIVER EXTRACT * )
Using rat liver alcohol:NAD+ oxidoreductase and aldehyde:NAD+ oxidoreductase, the following facts were found: 1) 3a-hydroxy-5~-cholestan-27-al was reduced to 5fi -cholestane-3a, 27-diol by liver alcohol: NAD+ oxidoreductase. 2) The optimum pH was pH 7. 0 with potassium phosphate buffer and pH 8. 5 with Tris buffer. 3) The Km value of the substrate to the enzyme was 14. 3 μM. 4) 3a-Hydroxy5fi-cholestan-27al was oxidized to 3a-hydroxy5fi-cholestan27-oic acid by liver aldehyde: NAD+ oxidoreductase. 5) The optimum pH was pH 8. 5 with Tris buffer. 6) The Km value of the substrate to the enzyme was 26. 3 μM.
Horse liver 3 ,7 ,12 -trihydroxy-5 -cholestan-26-al dehydrogenase as a liver aldehyde dehydrogenase.
Abstract 3α,7α,12α-Trihydroxy-5β-cholestan-26-al dehydrogenase (3α,7α,12α-trihydroxy-5β-cholestan-26-al + NAD+ + H2O → 3α,7α,12α-trihydroxy-5β-cholestan-26-oic acid + NADH + H+) in a soluble fraction of horse liver was studied. 1. 1. Horse liver 3α,7α,12α-trihydroxy-5β-cholestan-26-al dehydrogenase consists of two components, the major one of which was purified about 70-fold by (NH4)2SO4 fractionation, gel filtration, ion-exchange column chromatography and hydroxylapatite column chromatography. 2. 2. 3α,7α,12α-trihydroxy-5β-cholestan-26-al dehydrogenase was always accompanied by liver aldehyde:NAD oxidoreductase (EC 1.2.1.3) activity, and the ratio of these two enzyme activities was not altered by purification. 3. 3. Both 3α,7α,12α-trihydroxy-5β-cholestan-26-al dehydrogenase and horse liver aldehyde:NAD+ oxidoreductase were reduced to a similar extent on inactivation of the purified enzyme by heating or by incubation with p-chloromercuribenzoate. 4. 4. The Km value for NAD+ of 3α,7α,12α-trihydroxy-5β-cholestan-26-al dehydrogenase was found to be roughly equal to that of liver aldehyde:NAD+ oxidoreductase. 5. 5. The possibility was discussed that both 3α,7α,12α-trihydroxy-5β-cholestan-26-al dehydrogenase and liver aldehyde:NAD+ oxidoreductase activities may be due to a single protein.
Dating of Historical Manuscripts Using Spectrometric Methods: A Mini-Review
An overview is provided of spectrometric methods useful for age estimation of historical manuscripts (medieval ones in particular), in order to confirm their authenticity. Individual methods (infrared and Raman spectroscopy, mass spectrometry, atomic emission spectroscopy, X-ray spectroscopy, and electron scanning microscopy) are discussed and examples of their application described. The following general strategy can be recommended for dating and/or authenticating of historical manuscripts. First of all, the pigment analysis should be carried out using Raman spectroscopy (distinguishing the period and modern pigments), followed by PIXE ink analysis (solving the question of ink homogeneity). Finally, the radiocarbon dating of the writing support, potentially supplemented by the ink dating using scanning Auger microscopy should be performed.