PROTEIN

Drg. Dwi Prijamoko, PhD

Instructional Aim

At the end of the lecture, you are expected to be able to:Explain protein synthesis, various AA, absorption and metabolism of AA

PROTEINMakes up a major part of living cells (20%)In most tissues is 2nd to water50% of the dry weight of cellsMuscle is protein

PROTEINConstracted of Amino Acid ChainArranged in carefully ordered sequencesIn each species of living organismUnchanging in each particular protein20 different AA, The combinations of these create so many diff. species

Amino Acid & Polypeptide Chain

Essential & Non-essential

Functional & Structural RolesStructure of cell membranesForm connective tissue (Collagen & Elastin)Form innert protein (Hair & Nails)Act as enzymes, plasma protein (albumin)Form antibodiesForms complexes with other molecules (nucleoprotein)Form contractile protein in muscle

SynthesisSynthesized in all cells in the bodyNot all cells manufacture the same proteinDepends on AA supply that can be linkedThe amount and type of protein synthesized is controlled by Genes through M-RNASynthesis can proceed if all AA required are supplied

If a single AA is missing, synthesis will be halted at a point where AA was to be insertedA deficiency in a particular AA does slow protein synthesis down.Certain protein can be broken down to supply AA, then synthesis can be proceed at a reduced rate

AA Metabolism

Source of Protein

Absorption & Metabolism

Metabolic Profile of Protein

Nitrogen Balance

Human requiredmentDepends on the Obligatory Nitrogen lostChildhood, where growth and Development is in progressAfter injury, surgery and recovery from illnessIn Chirrotic patient, Protein absorption and metabolism is disturbed.

Protein free diet on urinary N out put

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