Metode Fizico-Chimice de Analiză Biochimică

Chapter I: Vitamins

1.1 General Presentation

• Vitamins: Exogenous organic compounds essential in small amounts for growth, development, and reproduction.
• Historical Context: Diseases like scurvy, beriberi linked to vitamin deficiencies.
• Kazimir Funk: Coined "vitamin" after isolating a substance curing beriberi.
• Deficiencies:
  • Total lack: Avitaminoses.
  • Single vitamin deficiency: Specific avitaminosis.
  • Multiple deficiencies: Polyavitaminosis.
  • Insufficient supply: Hypovitaminoses.
  • Excess supply: Hypervitaminoses.
• Provitamins: Precursors converted into vitamins inside the body.
• Antivitamins: Substances antagonistic to vitamins.

1.2 Nomenclature and Classification

• Nomenclature based on physiological action and discovery order.
• IUPAC Nomenclature proposed in 1966.
• Classification into hydrosoluble (B, C) and liposoluble (A, D, E, K) vitamins.
• Coenzymes and non-coenzymes classification.

1.3 Hydrosoluble Vitamins

• Vitamin B1 (Thiamine):

  • Sources: Grain hulls, yeast, milk, liver.
  • Structure: Contains pyrimidine and thiazolic nucleus.
  • Role: Coenzyme in enzyme reactions, stimulates lipid biosynthesis, regulates sugar metabolism.
  • Deficiency: Causes beriberi, nervous system disorders.

• Vitamin B2 (Riboflavin):

  • Sources: Egg white, milk, liver, yeast.
  • Structure: Includes isoalloxazine methylate and ribitol.
  • Role: Coenzymes FMN and FAD involved in metabolic reactions.
  • Deficiency: Causes mouth and digestive tract issues, decrease in vitamin PP.

• Vitamin B6 (Pyridoxine):

  • Sources: Plant and animal tissues, microbial flora.
  • Structure: Derivatives of pyridine: pyridoxol, pyridoxal, pyridoxamine.
  • Role: Enzyme cofactor for amino acid metabolism.
  • Deficiency: Causes dermatitis, anemia, nervous system disorders.

• Pantothenic Acid (Vitamin B3):

  • Sources: Yeast, rice hulls.
  • Role: Constituent of coenzyme A, involved in metabolism.
  • Deficiency: Causes growth issues, chicken pellagra.

• Nicotinamide (Vitamin PP):

  • Sources: Animal and vegetable products.
  • Structure: Nicotinic acid and nicotinamide.
  • Role: Component of NAD+ and NADP+ coenzymes.
  • Deficiency: Causes pellagra, gastrointestinal disorders.

• Biotin (Vitamin H):

  • Sources: Liver, milk, egg yolk.
  • Role: Enzyme cofactor in carboxylation and decarboxylation.
  • Deficiency: Rare, causes skin disorders.

• Mesoinositol (Bios Factor I):

  • Sources: Animal and plant tissues.
  • Role: Growth factor, involved in various metabolic processes.
  • Deficiency: Causes hair loss, growth retardation.

• Para-aminobenzoic Acid (PAB):

  • Role: Component of folic acids, antioxidant.
  • Interferes with sulfonamides.

• Pteroglutamic Acids (Folic Acids):

  • Sources: Green plants, liver.
  • Role: Coenzymes in nucleotide synthesis and metabolism.
  • Deficiency: Causes anemia, growth and development issues.

• Corionids (Vitamin B12):

  • Sources: Animal tissues like liver, kidney.
  • Structure: Cyanocobalamin with cobalt atom.
  • Role: Coenzyme in hematopoiesis and nucleic acid synthesis.
  • Deficiency: Causes pernicious anemia, neurological issues.

• Lipoic Acid:

  • Sources: Liver, yeast.
  • Role: Coenzyme in redox reactions.

• Pangamic Acid:

  • Sources: Plants, liver.
  • Role: Methylation and transmethylation reactions.

• B Complex Vitamins: Include B1, B2, B3, B5, B6, B9, B12, etc. Important for metabolism.

• Ascorbic Acid (Vitamin C):

  • Sources: Plant kingdom, animal tissues.
  • Role: Antioxidant, involved in various metabolic processes.
  • Deficiency: Causes scurvy.

• Bioflavonoids (Vitamin P):

  • Sources: Citrus fruits, peppers.
  • Role: Enhances vitamin C effect, improves capillary resistance.
  • Deficiency: Increases capillary permeability.

1.4 Liposoluble Vitamins

• Retinols (Vitamin A):

  • Sources: Liver, milk, egg yolk, fish oil.
  • Role: Growth, vision, immune function.
  • Deficiency: Causes skin lesions, vision problems.

• Calciferols (Vitamin D):

  • Sources: Skin, liver, egg yolk, fish oil.
  • Role: Bone health, calcium regulation.
  • Deficiency: Causes rickets, osteoporosis.

• Tocopherols (Vitamin E):

  • Sources: Green leaves, oils.
  • Role: Antioxidant, reproductive health.
  • Deficiency: Affects reproduction, muscles, cardiovascular system.

• Vitamins K:

  • Sources: Alfalfa, cabbage, liver.
  • Role: Blood coagulation.
  • Deficiency: Causes bleeding disorders.

• Ubiquinones: Related to tocopherols, involved in respiratory chain.

• Vitamins F (Essential Fatty Acids): Involved in lipid metabolism.

Chapter II: Enzymes

2.1 General Considerations

• Enzymes: Catalytic proteins facilitating chemical alterations.
• Enzymology: Study of enzyme structure and functionality.

2.2 Enzymes vs Industrial Catalysts

• Enzymes catalyze specific reactions, are not consumed, and function under mild conditions.
• Exhibit high specificity and efficiency.
• Participate in regulation and control within cells.

2.3 Structural Characteristics

• Enzymes have primary, secondary, tertiary, and sometimes quaternary structures.
• Holoprotein Structure: Made of amino acid chains forming catalytic sites.
• Heteroprotein Structure: Include non-protein groups like coenzymes or metal ions.
• Role of cofactors in enzymatic reactions.

2.4 Types of Enzymes

• Monomer Enzymes: Single polypeptide chain.
• Oligomer Enzymes: Multiple subunits or protomers.
• Isoenzymes: Different forms of an enzyme catalyzing the same reaction.
• Multienzyme Systems: Catalyze chained reactions.

2.5 Enzyme Specificity

• Substrate Specificity: Absolute or relative.
• Action Specificity: Catalyzing specific chemical reactions.

2.6 Enzyme-Substrate Complexes

• Formation involves transient bonding.
• Theories: Key-lock hypothesis, induced-fit hypothesis.

2.7 Kinetics of Enzymatic Reactions

• Michaelis-Menten Equation: Relationship between reaction speed and substrate concentration.
• Factors influencing kinetics: enzyme concentration, temperature, pH, effectors.

2.8 Regulation of Enzymes

• Allosteric Enzymes: Modulated by effectors.
• Covalently Modulated Enzymes: Altered through covalent bonds.

2.9 Enzyme Classification

• Based on reaction type: Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, Ligases.

Chapter III: Hormones

3.1 General Concepts

• Hormones influence physiological processes in the body.
• Endocrine System: Includes glands like hypothalamus, pituitary, thyroid, pancreas, etc.

3.2 Regulation of Hormonal Secretion

• Regulation through nervous and humorous pathways.
• Hypothalamo-Pituitary Axis: Central to neuro-endocrine regulation.

3.3 Transport and Elimination

• Hormones transported via blood, lymph, neurocrine pathways.
• Eliminated through urine, sometimes saliva and sweat.

3.4 Hormone Classification

• Classified by gland, process, chemical structure.
• Mechanism-based classification: Intracellular receptor binding, second messenger systems.

3.5 Mechanism of Action

• Hormones act through specific receptors.
• Peptide and Protein Hormones: Often use cAMP as a second messenger.
• Steroid Hormones: Bind intracellular receptors, influencing DNA transcription.

3.6 Peptide and Protein Hormones

• Hypothalamus Hormones: Releasing factors like GRF, CRF, TRF.
• Adenohypophysis Hormones: STH, ACTH, TSH, gonadotropic hormones.
• Neurohypophysis Hormones: Vasopressin, oxytocin.
• Pancreatic Hormones: Insulin, glucagon.
• Calcitonin: Regulates calcium levels.
• Parathyroid Hormone: Regulates calcium-phosphorus metabolism.
• Gastrointestinal and Renal Hormones: Influence digestive secretions and blood pressure.

3.7 Hormones Derived from Amino Acids

• Thyroid Hormones: T3, T4 regulate metabolism.
• Catecholamines: Adrenaline, noradrenaline affect cardiovascular and metabolic functions.
• Epiphyseal Hormones: Melatonin regulates biorhythms.
• Neurotransmitters: Serotonin, histamine influence nervous and vascular functions.

3.8 Steroid Structure Hormones

• Sex Hormones: Androgens, estrogens, gestagens.
• Adrenal Cortical Hormones: Glucocorticoids, mineralocorticoids.

3.9 Hormones with Fatty Acids Structure

• Prostaglandins: Influence reproductive, cardiovascular, and metabolic functions.