(+) 



LDH - I 



2 



ORIGIN 



(-) 



It 



V 1^ 



v.^-.^^. 





>'^J^^^ 



Fig. 6. 



Zymogram of the LDH Isozyme patterns of selected tis- 

 sues of the adult mouse. Note that each of the tissues 

 possesses a distinct proportion of the Isozymes. Equal 

 allquots of total enzyme activity from each tissue were 

 applied to the origin. 



Fig. 5. 



Zymogram of the LDH Isozyme patterns of adult Rhesus 

 monkey tissues. Each tissue Is distinguishable by the 

 relative proportions of the isozymes that it contains. 

 Adult heart muscle is rich In LDH-1 and -2 while the 

 proportion of these fast moving loszymes is strikingly 

 reduced or essentially absent in adult skeletal muscle 

 In which LDH-3, -4 and -5 predominate. Note, however, 

 that all five of the major isozymes are present in most 

 tissues albeit in different proportions. (From Markert, 

 in The Harvey Lectures, Series 59, 187, 1965; reproduced 

 with permission of Academic Press.) 



talline preparations which contained several of 

 the isozymes. The pure isozymes were subse- 

 quently hydrolyzed and their constituent amino 

 acids were analyzed by the method of Moore, 

 Spackman, and Stein (12). The results of such 

 analyses, shown in Table II, establish unequiv- 

 ocally that from the standpoint of amino acid 

 composition the two kinds of subunits are dif- 

 ferent proteins. In addition, in full accord with 

 the subunit hypothesis, LDH-3 consisting of 2 

 A and 2 B subunits, was shown to have an 

 amino acid composition intermediate between 

 that of LDH-1 and LDH-5 (13, 14). The amino 

 acid analyses also revealed that beef heart 

 LDH-1 contains 128 arginine and lysine resi- 

 dues calculated on the basis of a molecular 

 weight of 135,000. Consequently, denaturation 

 followed by trypsin digestion would be expected 



Fig. 7. 



Zymogram demonstrating the shift in LDH isozyme pat- 

 terns during development of representative tissues of the 

 mouse. The negative numbers along the abscissa indicate 

 days before birth and the positive numbers indicate days 

 after birth. The numbers along the ordinate designate the 

 isozymes. With time, there is an increase in LDH activity 

 at the anodal end of the electrophoretic spectrum and a 

 concomitant decrease at the cathodal end. 



81 



