RESUMO
Protein phosphorylation is a common signaling mechanism in both prokaryotic and eukaryotic organisms. Whilst serine, threonine and tyrosine phosphorylation dominate much of the literature there are several other amino acids that are phosphorylated in a variety of organisms. Two of these phosphoamino acids are phosphoarginine and phospholysine. This review will focus on the chemistry and biochemistry of both phosphoarginine and phospholysine. In particular we focus on the biological aspects of phosphoarginine as a means of storing and using metabolic energy (in place of phosphocreatine in invertebrates), the chemistry behind its synthesis and we examine the chemistry behind its highenergy phosphoramidate bond. In addition we will be reporting on the incidence of phosphoarginine in mammalian cells. Similarly we will be reviewing the current findings on the biology and the chemistry of phospholysine and its involvement in a variety of biological systems.
Assuntos
Arginina/análogos & derivados , Fosfosserina/química , Proteínas/química , Animais , Arginina/química , Arginina/metabolismo , Humanos , Cinética , Modelos Químicos , Estrutura Molecular , Compostos Organofosforados/química , Compostos Organofosforados/metabolismo , Fosforilação , Fosfosserina/metabolismo , Proteínas/metabolismo , TermodinâmicaRESUMO
Phosphohistidine has been identified as an enzymic intermediate in numerous biochemical reactions and plays a functional role in many regulatory pathways. Unlike the phosphoester bond of its cousins (phosphoserine, phosphothreonine and phosphotyrosine), the phosphoramidate (P-N) bond of phosphohistidine has a high DeltaG degrees of hydrolysis and is unstable under acidic conditions. This acid-lability has meant that the study of protein histidine phosphorylation and the associated protein kinases has been slower to progress than other protein phosphorylation studies. Histidine phosphorylation is a crucial component of cell signalling in prokaryotes and lower eukaryotes. It is also now becoming widely reported in mammalian signalling pathways and implicated in certain human disease states. This review covers the chemistry of phosphohistidine in terms of its isomeric forms and chemical derivatives, how they can be synthesized, purified, identified and the relative stabilities of each of these forms. Furthermore, we highlight how this chemistry relates to the role of phosphohistidine in its various biological functions.
