Subunit structure and amino acid composition of crystallized human muscle glycogen phosphorylase

S. A. Assaf, Adel A Yunis

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Electrophoresis in the presence of sodium dodecylsulfate gave a molecular weight of 94,500 for the monomer. When studied at 1 mg/ml and 20°C by high speed sedimentation equilibrium, sucrose density gradient ultracentrifugation and specific activity concentration dependence, both a and b forms of the human enzyme were found to exist as dimers. A slight association of human phosphorylase a was observed in the high speed sedimentation equilibrium values of the z average molecular weight (262,000 for M(z) vs 188,000 daltons for M(2)). Some association of the a enzyme was also detected by schlieren sedimentation velocity when the enzyme was studied at 5 mg/ml. Human phosphorylase b could be fully associated to tetramer at 20°C when P(i) Mg2+ and AMP were added but not in the presence of NaF and AMP which were found to be effective in tetramerizing rabbit phosphorylase b. Another important difference from rabbit phosphorylase was the significantly lower proline content of the enzyme from human muscle.

Original languageEnglish (US)
Pages (from-to)282-289
Number of pages8
JournalEuropean Journal of Biochemistry
Volume35
Issue number2
StatePublished - 1973

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Glycogen Phosphorylase
Muscle
Phosphorylase b
Sedimentation
Amino Acids
Muscles
Enzymes
Adenosine Monophosphate
Chemical analysis
Molecular Weight
Molecular weight
Phosphorylase a
Association reactions
Rabbits
Phosphorylases
Ultracentrifugation
Electrophoresis
Proline
Dimers
Sucrose

ASJC Scopus subject areas

  • Biochemistry

Cite this

Subunit structure and amino acid composition of crystallized human muscle glycogen phosphorylase. / Assaf, S. A.; Yunis, Adel A.

In: European Journal of Biochemistry, Vol. 35, No. 2, 1973, p. 282-289.

Research output: Contribution to journalArticle

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