Biomaterial Database

Cooperative effects in the binding of pyridoxal 5'-phosphate to mitochondrial apo-aspartate aminotransferase. 1984

A M Garzillo, and G Marino, and B Pispisa

Titrations of mitochondrial apo-aspartate aminotransferase with pyridoxal 5'-phosphate in the presence of AMP, contrary to what has been observed in the case of the cytosolic isoenzyme [(1983) FEBS Lett. 153, 98-102], show sigmoidal isotherms, with Hill coefficients ranging from nH = 1.4, in the absence of AMP, to nH = 1.8, in the presence of 5.9 mM AMP. The experimental data were successfully fitted by the Monod-Wyman- Changeaux model. The best fit, in the absence of AMP, was obtained with L = 30, KR = 4.72 X 10(-7) M and KT = 1.18 X 10(-5) M. Binding curves in the presence of AMP fit the model by keeping KR as a constant. This implies that AMP could bind to the apoenzyme only in the T state. In contrast, binding curves in the presence of phosphate ion (Pi) showed a less pronounced cooperativity, the Hill coefficient dropping to nH = 1.0 in the presence of 0.1 mM Pi. The above results suggest a regulatory role of AMP and Pi in the reconstitution of aspartate aminotransferase.

UI	MeSH Term	Description	Entries
D008929	Mitochondria, Heart	The mitochondria of the myocardium.	Heart Mitochondria,Myocardial Mitochondria,Mitochondrion, Heart,Heart Mitochondrion,Mitochondria, Myocardial
D010710	Phosphates	Inorganic salts of phosphoric acid.	Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D011732	Pyridoxal Phosphate	This is the active form of VITAMIN B 6 serving as a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into pyridoxamine phosphate (PYRIDOXAMINE).	Pyridoxal 5-Phosphate,Pyridoxal-P,Phosphate, Pyridoxal,Pyridoxal 5 Phosphate,Pyridoxal P
D003600	Cytosol	Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.	Cytosols
D000249	Adenosine Monophosphate	Adenine nucleotide containing one phosphate group esterified to the sugar moiety in the 2'-, 3'-, or 5'-position.	AMP,Adenylic Acid,2'-AMP,2'-Adenosine Monophosphate,2'-Adenylic Acid,5'-Adenylic Acid,Adenosine 2'-Phosphate,Adenosine 3'-Phosphate,Adenosine 5'-Phosphate,Adenosine Phosphate Dipotassium,Adenosine Phosphate Disodium,Phosphaden,2' Adenosine Monophosphate,2' Adenylic Acid,5' Adenylic Acid,5'-Phosphate, Adenosine,Acid, 2'-Adenylic,Acid, 5'-Adenylic,Adenosine 2' Phosphate,Adenosine 3' Phosphate,Adenosine 5' Phosphate,Dipotassium, Adenosine Phosphate,Disodium, Adenosine Phosphate,Monophosphate, 2'-Adenosine,Phosphate Dipotassium, Adenosine,Phosphate Disodium, Adenosine
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001051	Apoenzymes	The protein components of enzyme complexes (HOLOENZYMES). An apoenzyme is the holoenzyme minus any cofactors (ENZYME COFACTORS) or prosthetic groups required for the enzymatic function.	Apoenzyme
D001059	Apoproteins	The protein components of a number of complexes, such as enzymes (APOENZYMES), ferritin (APOFERRITINS), or lipoproteins (APOLIPOPROTEINS).	Apoprotein