CH. XIV. 



Fluid red 



PIGMENTS AND ENZYMES. 

 Acid Acid haematoporphyrin, two bands. (Ex. 307.) 



36; 



Neutral 



lAlkaline 



Dilute till two 



bands are well 



seen and then 



reduce. 



Oxy haemoglobin, the two bands 

 merge into one faint band (Ex 

 293.) 



CO -haemoglobin, the two bands 

 are unaltered. (Ex. 296.) 



Alkaline haematoporphyrin, feur bands,, converted 

 into acid haematoporphyrin by strong acids. (Exs. 

 307 and 308.) 



Haemochromogen, two bands in green, one much 

 more distinct than the other, unaffected by reduc- 

 ing reagents. (Ex. 305.) 



Fluid brown 



Acid Acid haematin, band in red. Ex. 301., 



Neutral. Methaemoglobin, band in red : gives spectrum of 

 oxy haemoglobin and then of reduced haemoglobin 

 if reduced. (Ex. 299.) 



Alkaline haematoporphyrin four bands. (Ex. 308.) 



V Alkaline - 



Alkaline haematin, faint band in red, converted to 

 haemochromogen by reducing reagents. (Exs. 

 303, 305.) 



Enzymes. 



In testing for enzymes it is important to note the reaction. "s!\It is not 

 necessary to determine the exact P H , but trials should be made with litmus, 

 followed by phenol-red and phenol-phthalein for alkaline solutions, and 

 methyl-red and brom-phenol-blue (or thymol-blue) for acid solutions. In this 

 way certain valuable indications may be obtained. 



The next point to remember is that all tests must be made in parallel with 

 a control. In the control test, the solution is well boiled to destroy any 

 enzyme that may be present : in other respects it is carried out exactly as the 

 test proper. Without this precaution it is quite impossible to make any safe 

 deduction. 



To test for proteolytic enzymes see if the solution will clot calcined milk 

 (Exs. 252 and 257) . The solution should be nearly neutralised before applying 

 the test, but if it is acid it must not be made alkaline (see Ex. 253). If this 

 test is positive, pepsin can be identified by the method given in Ex. 248. 

 Rennin can be distinguished from pepsin by Ex. 256, though it takes a good 

 deal of time. It is unusual to find a rennin solution free from pepsin, but many 

 commercial pepsins are practically free from true rennin. Trypsin can be 

 identified by Ex. 258. 



