Biochemistry Lecture 8 PDF

Biochemistry Protein LECTURE (8) DR. El-Sawy 1  Biochemistry Protein  Organi...

Biochemistry Protein LECTURE (8) DR. El-Sawy 1  Biochemistry Protein  Organic complex nitrogenous compounds of high MW.  Formed of C, H, O, N, [N= 16%]. Def :  Formed of a number of amino acids linked together by peptide linkage [-CO-NH-].  Antibodies (immunoglobulin). ‫اجسام مضادة‬  Buffer system of blood (plasma proteins). ‫ومعادلة‬  Carry hormones & minerals in blood. functions :  Carry oxygen (Hemoglobin).  Structure of cell membrane. ‫تركيب‬  Support bone, skin, nails & hair. ‫ودعامة‬  Hormones as insulin.  Enzymes.  According to shape. Classification  According to nutritional value.  According to structure. DR. El-Sawy 2  Biochemistry Protein According to shape : Fibrous Globular Shape Long , narrow fiber Rounded (spherical) Axial More than 10 Less than 10 ratio Water Insoluble Soluble solubility Stability More stable Less stable Example Actin , Myosin ,Collagen Albumin , hemoglobin , insulin DR. El-Sawy 3  Biochemistry Protein According to nutritional value : Nutritionally Incomplete proteins Poor proteins rich proteins Lack many essential Structure All essential A.A. Lack one essential A.A. A.A.  Proteins of pulses  Zein of maize  Caseinogen of deficient in methionine Example lacks tryptophan milk  Proteins of cereals & lysine deficient in lysine. According to structure : Simple protein  On hydrolysis , produce mainly A.A. Conjugated  Formed of protein & non protein part (Compound) Protein  Denaturated or hydrolytic products of simple or Derived protein conjugated protein DR. El-Sawy 4  Biochemistry Protein A. Simple proteins  Water insoluble.  Water insoluble.  Water insoluble. Solubility  Water soluble.  Soluble in dilute salt solution.  Soluble in dilute acids & alkali.  Soluble in dilute acids & alkali Coagulation Coagulated by heat. Not coagulated by heat.  Egg (egg albumin).  Egg (egg globulin).  Gliadein of wheat.  Blood (plasma albumin).  Blood (plasma globulin).  Zein of corn & maize Site  Glutenin of wheat.  Milk (lactoalbumin).  Milk (lactoglobulin). (deficient in tryptophan)→  Plant (cereals)  Muscle (Myoglobin) pellagra. DR. El-Sawy 5  Biochemistry Protein  Water insoluble. Solubility  Water soluble.  Water soluble and in dilute acids.  Insoluble in dilute acids , alkali & all neutral solvents Coagulation Not coagulated by heat. Keratin In hair & nail Rich in sulfer amino acids In joints, ligaments Elastin Rich in proline, valine and alanine Rich in basic amino acids & lung alveoli Example (+ve charged). Rich in glycine, hydroxyl-proline In skin , bone, Collagen and hydoxy-lysine cartilage & CT By boiling it converted to gelatin  In combination with nucleic acid in  Animal tissues → supportive& protective.  In combination with nucleic Site human.  Not digested by proteolytic enzymes acid in salmon fish.  Present in globin of hemoglobin.  They are fibrous proteins. Gelatin: Easily digested , forming gel by cooling. It is not adequate diet as deficient in certain essential amino acids as tryptophan. DR. El-Sawy 6  Biochemistry Protein B. Conjugated (Compound) proteins  Proteins are  Proteins are  Proteins  Proteins are  Proteins are Def conjugated with conjugated with conjugated with conjugated with  Proteins with apical colors. conjugated with carbohydrate. lipids phosphoric acid. metals. nucleic acids. 1. Hemoproteins:  Caseinogen  Hormones : (FSH,LH). Protein + heme (red (main protein of  Ceruoplasmin :  Enzymes. pigment) as Hb &  Chylomicrons. milk). protein + Cu.  Histone + DNA  Antibodies. cytochromes (components  VLDL.  NB: Phosphoric  Insulin : in chromosome.  Blood group of Electron transport Example  LDL. acid is attached protein + Zinc.  Protein + RNA antigen. chain (ETC))  HDL. to protein by OH  Ferritin: in Ribosome.  Mucin of GIT. 2. Flavo-proteins : group of seine , protein + Fe. HEAM Proteins + FAD or FMN threonine AA. (yellow color). DR. El-Sawy 7  Biochemistry Protein C. Derived proteins Def  Denaturated or hydrolytic products of simple or conjugated proteins. Primary Secondary  Alteration of proteins from its native state without hydrolysis of Result from  These are hydrolytic products of proteins. peptide bond. Types Meta-proteins Coagulated proteins Proteoses Peptones Peptides  Products of protein denaturation  Products of protein  Products of partial  Products of  Products of Def by acid or alkalis. denaturation by heat. proteins hydrolysis. proteoses hydrolysis peptones hydrolysis Example  Acid or alkali meta protein  Cooked egg albumin. Coagulation Coagulated by heat Not coagulated by heat DR. El-Sawy 8