Biomaterial Database

Nuclease digestion of synthetase x tRNA complexes. 1975

W Hörz, and D Meyer, and H G Zachau

Phenylalanyl-tRNA and seryl-tRNA synthetase protect strongly though not completely their cognate tRNAs against nuclease attack, as had been shown previously. In an investigation of the mechanism of protection it was demonstrated that the low susceptibility of phenylalanyl-tRNA-synthetase x tRNA-Phe complexes to nucleases is due to free tRNA present in equilibrium with synthetase. The equilibrium can be shifted by an excess of synthetase or by dilution of the complex. It therefore appears that synthetase competes with the nuclease for free tRNA. Degradation of the complex is low, however, because under the conditions of partial digestion the synthetase has a greater affinity for the tRNA than does the nuclease. Fragmented tRNAs, as they are formed during partial nuclease digestion, bind to synthetase to different degrees. tRNA-Phe with a lesion in the dihydrouridine loop binds very poorly whereas a nick in the anticodon loop reduces the strength of binding to a much lesser extent. In a systematic study of the stoichiometry of protection it was confirmed that under standard conditions one phenylalanyl-tRNA synthetase protects one tRNA-Phe and one seryl-tRNA synthetase two tRNA-Ser molecules against nuclease attack. Under certain conditions, however, (concentration of the complex higher than 10 mu-M, or alternately in buffers of low ionic strength) it is observed that phenylalanyl-tRNA synthetase binds up to 1.6 molecules tRNA-Phe. In the serine system, these special conditions do not affect the binding properties of seryl-tRNA synthetase.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010179	Pancreas	A nodular organ in the ABDOMEN that contains a mixture of ENDOCRINE GLANDS and EXOCRINE GLANDS. The small endocrine portion consists of the ISLETS OF LANGERHANS secreting a number of hormones into the blood stream. The large exocrine portion (EXOCRINE PANCREAS) is a compound acinar gland that secretes several digestive enzymes into the pancreatic ductal system that empties into the DUODENUM.
D010649	Phenylalanine	An essential aromatic amino acid that is a precursor of MELANIN; DOPAMINE; noradrenalin (NOREPINEPHRINE), and THYROXINE.	Endorphenyl,L-Phenylalanine,Phenylalanine, L-Isomer,L-Isomer Phenylalanine,Phenylalanine, L Isomer
D010652	Phenylalanine-tRNA Ligase	An enzyme that activates phenylalanine with its specific transfer RNA. EC 6.1.1.20.	Phenylalanyl T RNA Synthetase,Phe-tRNA Ligase,Phenylalanyl-tRNA Synthetase,Ligase, Phe-tRNA,Ligase, Phenylalanine-tRNA,Phe tRNA Ligase,Phenylalanine tRNA Ligase,Phenylalanyl tRNA Synthetase,Synthetase, Phenylalanyl-tRNA
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
D004589	Electrophoresis, Disc	Electrophoresis in which discontinuities in both the voltage and pH gradients are introduced by using buffers of different composition and pH in the different parts of the gel column. The term 'disc' was originally used as an abbreviation for 'discontinuous' referring to the buffers employed, and does not have anything to do with the shape of the separated zones.	Electrophoresis, Disk,Disc Electrophoresis,Disk Electrophoresis
D000604	Amino Acyl-tRNA Synthetases	A subclass of enzymes that aminoacylate AMINO ACID-SPECIFIC TRANSFER RNA with their corresponding AMINO ACIDS.	Amino Acyl T RNA Synthetases,Amino Acyl-tRNA Ligases,Aminoacyl Transfer RNA Synthetase,Aminoacyl-tRNA Synthetase,Transfer RNA Synthetase,tRNA Synthetase,Acyl-tRNA Ligases, Amino,Acyl-tRNA Synthetases, Amino,Amino Acyl tRNA Ligases,Amino Acyl tRNA Synthetases,Aminoacyl tRNA Synthetase,Ligases, Amino Acyl-tRNA,RNA Synthetase, Transfer,Synthetase, Aminoacyl-tRNA,Synthetase, Transfer RNA,Synthetase, tRNA,Synthetases, Amino Acyl-tRNA
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D012260	Ribonucleases	Enzymes that catalyze the hydrolysis of ester bonds within RNA. EC 3.1.-.	Nucleases, RNA,RNase,Acid Ribonuclease,Alkaline Ribonuclease,Ribonuclease,RNA Nucleases,Ribonuclease, Acid,Ribonuclease, Alkaline
D012343	RNA, Transfer	The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.	Suppressor Transfer RNA,Transfer RNA,tRNA,RNA, Transfer, Suppressor,Transfer RNA, Suppressor,RNA, Suppressor Transfer