VII. ESTIMATION 



471 



enzyme preparations, almost all of them proteolytic, have l)een pro- 

 posed^"- ^^'^^ for the release of the vitamin activity. Peeler et al*^ found a 

 pancreatin treatment of animal products and a papain-takadiastase treat- 

 ment of \'egetahle materials to be superior to hot- or cold-water extractions 

 at N'arious pH's. Scheid and Schweigert^" found considerable difficulty in 

 obtaining consistent results after enzyme digestion. Pancreatin gave ap- 

 proximately a twofold increase in the vitamin B]2 potency of beef liver and 

 increases in other meat products. A recent report by these workers^- is 

 perhaps the most thorough report on release with various enzyme prepara- 



RESPONSE OF E.COLI TO VITAMIN B,, 

 WITH THE PftD PLATE METHOD 



MILLIMICROGRAMS VITAMIN B PER PAD 



Fig. 7. The response of E. coli 113-3 to vitamin B12 in the pad-plate method. 

 Measurements were taken from plate shown in Fig. 2. 



tions and heat treatments. Crude preparations of trypsin, pancreatin, chick 

 pancreas, takadiastase, and filtrates of proteolytic bacteria all increased 

 the apparent \ntamin B12 content of beef liver, beef round, and a few other 

 meats approximately twofold. Autoclaving the tissues at neutral pll in 

 phosphate buffer resulted in values only 5 to 10% less than the enzyme 

 various treatments. In an extensive collaborative study carried out by the 

 Association of Official Agricultural Chemists, ^^ hot aqueous extraction was 

 found superior to trypsin digestion. The most consistent and highest values 

 were obtained by autoclaving 0.1 to 1.0 g. of sample 15 minutes with 25 



"H. T. Thompson, L. S. Dietrich, and C. A. Elvehjem, /. Biol. Chcm. 184, 175 



(1950). 

 «» H. E. Scheid and B. S. Schweigert, J. Biol. Chem. 185, 1 (1950). 

 «' J. R. Couch and O. Olcese, /. Nutrition 42, 337 (1950). 

 62 H. E. Scheid and B. S. Schweigert, J. Biol. Chem. 193, 299 (1951). 

 6^ C. H. Krieger, Personal communication. 



