https://search.dev.ndltd.org/etd/massey/oai:mro.massey.ac.nz:10179/3302
type: CreativeWork
name: Sheep liver phosphofructokinase : a comparison of the primary structure with those of other mammalian isozymes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biochemistry at Massey University
description: Phosphofructokinase (PFK) is the key regulatory enzyme of glycolysis, catalysing the synthesis of fructose 1,6-bisphosphate from fructose 6-phosphate and ATP. Several PFK isozymes have been identified from different tissues, including muscle, liver and platelet. Each isozyme is under the control of a different structural locus in humans the muscle isozyme gene is carried on chromosome 1, liver on chromosome 21, and platelet on chromosome 10. The tetramer of PFK is the lowest active form, and there are both species and tissue differences in the composition of the tetramer. Some, such as human muscle PFK consist of four identical subunits (M4), whereas others, such as human erythrocyte PFK comprise a five membered isozyme system, made up of both muscle and liver subunits. The activity of PFK is modulated by a variety of effectors such as; ATP, fructose 6-phosphate, ADP, AMP and fructose 2,6-bisphosphate, as well as covalent modification, and hormonal regulation. Each PFK isozyme exhibits its own characteristic kinetic properties in response to changes in effector concentrations. This project aims to compare the primary structures of two PFK isozymes; liver and muscle, from a single species (sheep), in order to explain their different kinetic properties in terms of differences in their primary structures. A purification procedure for sheep liver PFK was developed, and a 48% yield was obtained, with a final specific activity of 100Units/mg of protein. Sodium dodecyl sulphate-gel electrophoresis indicated a protomer molecular weight of 84 000 for sheep heart muscle PFK, and 81 000 for sheep liver PFK, indicating that liver PFK is approximately 30 residues shorter than the muscle enzyme. The comparison of the amino acid compositions showed a significantly lower arginine and lysine content in liver PFK compared to muscle PFK. There was also a lower threonine content in liver PFK, accompanied by an increase in the number of serine residues, compared to muscle PFK. So overal…
abstract: Phosphofructokinase (PFK) is the key regulatory enzyme of glycolysis, catalysing the synthesis of fructose 1,6-bisphosphate from fructose 6-phosphate and ATP. Several PFK isozymes have been identified from different tissues, including muscle, liver and platelet. Each isozyme is under the control of a different structural locus in humans the muscle isozyme gene is carried on chromosome 1, liver on chromosome 21, and platelet on chromosome 10. The tetramer of PFK is the lowest active form, and there are both species and tissue differences in the composition of the tetramer. Some, such as human muscle PFK consist of four identical subunits (M4), whereas others, such as human erythrocyte PFK comprise a five membered isozyme system, made up of both muscle and liver subunits. The activity of PFK is modulated by a variety of effectors such as; ATP, fructose 6-phosphate, ADP, AMP and fructose 2,6-bisphosphate, as well as covalent modification, and hormonal regulation. Each PFK isozyme exhibits its own characteristic kinetic properties in response to changes in effector concentrations. This project aims to compare the primary structures of two PFK isozymes; liver and muscle, from a single species (sheep), in order to explain their different kinetic properties in terms of differences in their primary structures. A purification procedure for sheep liver PFK was developed, and a 48% yield was obtained, with a final specific activity of 100Units/mg of protein. Sodium dodecyl sulphate-gel electrophoresis indicated a protomer molecular weight of 84 000 for sheep heart muscle PFK, and 81 000 for sheep liver PFK, indicating that liver PFK is approximately 30 residues shorter than the muscle enzyme. The comparison of the amino acid compositions showed a significantly lower arginine and lysine content in liver PFK compared to muscle PFK. There was also a lower threonine content in liver PFK, accompanied by an increase in the number of serine residues, compared to muscle PFK. So overal…
author: Rutherfurd, Kay Jenice
keywords: Phosphofructokinases, Sheep liver, Mammalian isozymes
date published: 1988
date modified: 2026-07-27T20:17:35Z
provider: Massey University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massey University