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ATP CYCLE

BIOCHEMISTRY

mprasadnaidu
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ATP CYCLE

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  1. Bio-inorganic chemistry ATP CYCLE M.Prasad Naidu MSc Medical Biochemistry, Ph.D.Research Scholar

  2. High energy compounds • The term high-E compounds or energy rich compounds is usually applied to substances which possess sufficient free E to liberate at least 7 Cal/mol at pH 7.0 • The compounds which liberate less than 7.0 Cal/mol are referred to as low-E compounds. • Most of the high E compounds contain PO43- (exception acetyl CoA) hence they are called high E phosphate compounds.

  3. High E compounds

  4. Low E Phosphates

  5. Classification of High E compounds • 1. Pyrophosphates e.g. ATP • 2. Acyl phosphates e.g. 1,3-bisphosphogly • 3. Enol phosphates e.g. PEP • 4. Thioesters e.g. acetyl CoA • 5. Phosphagenes e.g. phosphocreatine

  6. ATP CYCLE • The living objects require a continuous supply of FE mainly for • 1. to synthesize macromolecules from simpler & smaller precursors • 2. to transport molecules and ions across membranes against gradients and • 3. to perform mechanical work, as in the muscle contraction etc.,

  7. ATP CYCLE • The FE in these processes is derived from the environment. • The phototrophs obtain this E by trapping light E from the SUN. • On the other hand, chemotrophs obtain it by the oxidation of food stuffs. • This FE is partly transformed into special form b4 it is used for biosynthesis, tpt, motion and fidelity. • This special carrier of FE is ATP. • ATP plays a central role in the transference of FE from exergonic to the endergonic processes in the cells.

  8. ATP CYCLE • ATP donates much of its chemical E to energy requiring processes (biosynthesis, transport) by undergoing a breakdown to ADP and Pi. • ATP was discovered in extracts of skeletal muscles by Karl Lohmann in GE and by Cyrus Fiske and Y.Subbarow (US) simultaneously in 1929. • Later it was found to be present in all types of cells- animal, plant and microbial.

  9. ATP CYCLE • Fritz.A.Lipmann a GE born US biochemist postulated that ATP is the 10 and universal carrier of chemical E in cells.(Nobel prize) • He also first proposed the ATP Cycle , and is popularly known as Father of ATP cycle. • He introduced squiggle notation to designate E rich bonds of biomolecules such as ATP and ADP.

  10. ATP CYCLE • ATP, ADP & AMP occur not only in cell cytosol but also in MC and the nucleus. • ATP serves as the principal immediate donor of FE in biological systems rather than as a storage form of E. • In a typical cell, an ATP molecule is consumed with in a minute of its formation. • The turnover of ATP is very high. • For instance , a resting human consumes about 40kg ATP in a day.

  11. ATP CYCLE • The endergonic processess such as bio- synthesis, active tpt etc can occur only if ATP is continuously regenerated from ATP • Phototrophs harvest the FE in light to regenerate ATP where as chemotrophs form ATP by the oxidation of food stuffs.

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