The Covalent Alteration of One or More Amino Acids Occurring in Proteins Peptides and Nascent Polypeptides (co Translational Post Translational Modifications) Occurring At the Level of an Individual Cell. Includes the Modification of Charged Trnas That Are Destined to Occur in a Protein (pre Translation Modification).
Interacting Selectively and Non Covalently with a Nucleotide Any Compound Consisting of a Nucleoside That Is Esterified with (ortho)phosphate or an Oligophosphate At Any Hydroxyl Group On the Ribose or Deoxyribose.
Catalysis of a Biochemical Reaction At Physiological Temperatures. in Biologically Catalyzed Reactions the Reactants Are Known As Substrates and the Catalysts Are Naturally Occurring Macromolecular Substances Known As Enzymes. Enzymes Possess Specific Binding Sites For Substrates and Are Usually Composed Wholly or Largely of Protein But RNA That Has Catalytic Activity (ribozyme) Is Often Also Regarded As Enzymatic.