Section 15 — Human Genetics 



15.84. Inherited Structural Variation of Human 

 Myoglobin. Samuel H. Boyer, David C. 

 Fainer, and Michael A. Naughton (Balti- 

 more, U.S.A.). 



Although considerable variation occurs a- 

 mong the hemoglobins of several species, no 

 such variation has been reported for myoglobin. 

 We shall describe examples of inherited struc- 

 tural alteration in myoglobin and indicate simple 

 methods for their detection. 



Myoglobin, obtained from autopsy and diag- 

 nostic muscle biopsy, was prepared by ultra- 

 filtration of crude muscle extracts. The ultra- 

 filtrate was subsequently examined by starch gel 

 electrophoresis at pH 8.5. These procedures 

 are simple, highly efficient and well suited for 

 characterization of large numbers of samples. 



Among 159 individuals, two subjects possessed 

 both normal myoglobin (Mb+) and an electro- 

 phoretically distinguishable variant. One of 

 these variants, Mb ATiercieen , migrates more 



slowly than Mb" while the other variant, 

 Mr>Annapoiis j migrates faster than Mb + . 



Mb Annapolis occurred in a mother and her 

 son both of whom were free of muscular and 

 cardiac disease. Mb + and Mb Annapolis are 

 similar in molecular weight and spectral ab- 

 sorption but differ in fingerprints of tryptic 

 digests. Mb Annapolis i ac k s two normally 

 present peptides, viz., 7 and 13, and possesses 

 a new peptide, X. Amino acid analysis of these 

 peptides and homology with sperm whale my- 

 oglobin suggest that the peptides are arranged: 

 NH-2 7 arginine/NH2 13 lysine 



The loss of arginine in Mb Annapolis accounts 

 for the altered fingerprint and the rapid migra- 

 tion of the whole molecule but has no apparent 

 influence on function. 



Detection and characterization of additional 

 myoglobin mutants may be helpful in the study 

 of certain muscular diseases as well as quite 

 useful in assigning function to various portions 

 of a molecule whose fine structure is particularly 

 well delineated. 



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