Abstract
Glycogen phosphorylase in cell-free extracts of Neurospora crassa is activated 10- to 15-fold by incubation with MgATP2-. When the MgATP2- is removed, the active form (a form) reverts to the inactive form (b form). The inactivation requires Mg2+ and is inhibited by NaF. The results confirm that Neurospora crassa glycogen phosphorylase exists in two interconvertible forms and strongly suggests that the interconversion is catalyzed by a kinase and phosphatase. The a form was partially purified. The enzyme has a molecular weight of 320,000. Uridine diphosphate glucose is a linear competitive inhibitor with respect to glucose-1-phosphate and a linear non-competitive inhibitor with respect to glycogen. Glucose-6-phosphate is a hyperbolic (partial) noncompetitive inhibitor with respect to all substrates in both directions. The b form of the enzyme in crude cell-free extracts is stimulated 2- to 3-fold by 5′-AMP. As the b form is purified, the 5′-AMP activation is diminished. The molecular weight of the partially purified "b" form was also 320,000.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 515-527 |
| Number of pages | 13 |
| Journal | Archives of Biochemistry and Biophysics |
| Volume | 161 |
| Issue number | 2 |
| DOIs | |
| State | Published - 1974 |
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ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Molecular Biology
Cite this
Neurospora crassa glycogen phosphorylase : Interconversion and kinetic properties of the "active" form. / Gold, Michael H.; Farrand, Robert J.; Livoni, John P; Segel, Irwin H.
In: Archives of Biochemistry and Biophysics, Vol. 161, No. 2, 1974, p. 515-527.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Neurospora crassa glycogen phosphorylase
T2 - Interconversion and kinetic properties of the "active" form
AU - Gold, Michael H.
AU - Farrand, Robert J.
AU - Livoni, John P
AU - Segel, Irwin H.
PY - 1974
Y1 - 1974
N2 - Glycogen phosphorylase in cell-free extracts of Neurospora crassa is activated 10- to 15-fold by incubation with MgATP2-. When the MgATP2- is removed, the active form (a form) reverts to the inactive form (b form). The inactivation requires Mg2+ and is inhibited by NaF. The results confirm that Neurospora crassa glycogen phosphorylase exists in two interconvertible forms and strongly suggests that the interconversion is catalyzed by a kinase and phosphatase. The a form was partially purified. The enzyme has a molecular weight of 320,000. Uridine diphosphate glucose is a linear competitive inhibitor with respect to glucose-1-phosphate and a linear non-competitive inhibitor with respect to glycogen. Glucose-6-phosphate is a hyperbolic (partial) noncompetitive inhibitor with respect to all substrates in both directions. The b form of the enzyme in crude cell-free extracts is stimulated 2- to 3-fold by 5′-AMP. As the b form is purified, the 5′-AMP activation is diminished. The molecular weight of the partially purified "b" form was also 320,000.
AB - Glycogen phosphorylase in cell-free extracts of Neurospora crassa is activated 10- to 15-fold by incubation with MgATP2-. When the MgATP2- is removed, the active form (a form) reverts to the inactive form (b form). The inactivation requires Mg2+ and is inhibited by NaF. The results confirm that Neurospora crassa glycogen phosphorylase exists in two interconvertible forms and strongly suggests that the interconversion is catalyzed by a kinase and phosphatase. The a form was partially purified. The enzyme has a molecular weight of 320,000. Uridine diphosphate glucose is a linear competitive inhibitor with respect to glucose-1-phosphate and a linear non-competitive inhibitor with respect to glycogen. Glucose-6-phosphate is a hyperbolic (partial) noncompetitive inhibitor with respect to all substrates in both directions. The b form of the enzyme in crude cell-free extracts is stimulated 2- to 3-fold by 5′-AMP. As the b form is purified, the 5′-AMP activation is diminished. The molecular weight of the partially purified "b" form was also 320,000.
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U2 - 10.1016/0003-9861(74)90334-8
DO - 10.1016/0003-9861(74)90334-8
M3 - Article
VL - 161
SP - 515
EP - 527
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 2
ER -