Bioinorganic Chemistry T.Y.B.Sc. 2015 PDF

BIOINORGANIC CHEMISTRY CH-342 Savitribai Phule Pune University, Pune T.Y.B.Sc. Chemistry Syllabus, Pattern – 2015 Inorganic Chemistry (CH-342), Semester-IV,...

BIOINORGANIC CHEMISTRY CH-342 Savitribai Phule Pune University, Pune T.Y.B.Sc. Chemistry Syllabus, Pattern – 2015 Inorganic Chemistry (CH-342), Semester-IV, Chapter -6 Introduction to Bio–Inorganic Chemistry Introduction: The Bio–inorganic chemistry is deals with branch of natural philosophy to understand the chemistry of reactions involving essential metals and other trace elements in living organisms. The number of metal ions plays an important role in biology. Some of the elements are essential for growth of human being. About 30 elements are found in human body. The elements H, C, N, O, P are present in bulk in living organism. Na, K, Mg, Ca, S, Cl, Mo, Fe, Co, Cu, Zn, I presents in small quantities, while Si, V, Cr, Se, Br, Sn, F, W, Li, Ni, As are found in ultra-trace quantities. Essentiality of elements is defined by 1) A physiological deficiency appears when the element is removed from the diet 2) The deficiency is relieved by the addition of that element to the diet 3) A specific biological function is associated with the element Physiologically relevant are the alkaline metal ions Na + and K+, and the alkaline earth metal ions Mg2+ and Ca2+. The Li+ is of therapeutic interest (treatment of mood disorders such as maniac depression; treatment of hypertension). The transition metal ion Mn2+ exhibits some similarities with Ca2+ and Mg2+. Amounts present in man (in g per 70 kg body weight)): Na -105, K -140, Mg - 35, Ca -1050 gms. Daily demand: Na 1.1-3.3, K 2.0-5.0, Mg 0.3-0.4, Ca 0.8-1.2 gms. With the exception of Mg2+, there are striking differences in the intra- and extra-cellular concentrations of these cations. This Table summarizes the intra- and extracellular concentrations of the more important cations and anions. It is also contains concentrations of these ions in sea-water, often considered “the cradle of life“. To maintain the “correct” concentration gradients between the cytosol and the extracellular space is of prime importance to ascertain the specific functions of these ions, such as controlling the osmotic pressure and cell membrane potentials, triggering signal transduction, and activating enzymes. Dr. Madhukar Navgire, Jijamata College of Science and Arts, Bhende 1  BIOINORGANIC CHEMISTRY CH-342 Overview of the functions (selection): Important roles for metal ions in biological systems are energy storage and release, oxygen transport and storage, enzyme action, electron transfer, nitrogen fixation and photosynthesis, etc.  Information transfer by migration along a concentration and/or electrochemical gradient: all ions  Support (endo- and exo-skeletons, teeth): Ca (and Mg)  Activation and regulation of enzymes: Ca (and Mg, K)  Signal transduction, e.g. in neurotransmission Ca, K  Chlorophyll: Mg  Phosphate and anaerobic energy metabolism; activation by phosphorylation: Mg  Stabilization of cell membranes by the formation of cross-links between membrane proteins and polysaccharides: Mg (and Ca)  Structural, charge carrier: Ca  Structural, hydrolase, isomerase: Mg, Zn  Charge carrier, Regulation of the osmotic pressure and of membrane potentials: Na, K  Hydrogenase, hydrolase: Ni  Dioxygen transport and storage, electron transfer, oxidase: Cu  Dioxygen transport, oxygen storage, electron transfer, oxidase, nitrogen fixation: Fe  Photosynthesis, structural, oxidase: Mn  Nitrogen fixation, oxidase, oxo transfer: V, Mo  Glucose tolerance: Cr  Dehydrogenase: W  Oxidase, Alkyl group transfer: Co  Hydrogenase, Hydrolase: Ni  Structure, hydrolase: Zn Biochemistry of Sodium and Potassium (Na/K):- In order to adjust to the intra-cellular (K+ is 0.15M and Na+ is 0.01M) and extra-cellular (K+ is 0.004M and Na+ is 0.15M) concentrations of Na+ and K+ it is essential that these ions can cross the membrane of the cells. Such a trans- membrane transport can be passive (via diffusion) or active by use of an ion pump. This transport mediators called ionophores. Alternatively, and more efficiently, the transport can occur along ion channels in the membrane. Dr. Madhukar Navgire, Jijamata College of Science and Arts, Bhende 2  BIOINORGANIC CHEMISTRY CH-342 The active transport for Na+ and K+ is achieved by a Na+/K+ specific pump. The energy necessary for the transport against a concentration gradient is provided by the hydrolysis of ATP. Na+(in) → Na+(ex) // K+(ex) → K+(in) MgATP hydrolyzed 2 K+ are locked in and 3 Na+ are locked out: MgATP- + 3Na+in + 2K+ex → MgADP + Pi- + 3Na+ex + 2K+in The charge imbalance thus produced is balanced, in part, by a Ca 2+-ATPase, Na+ and in part by passive transport. Misbalancing of Na/K Low Na (hyponatremia): Possible causes of sodium deficiencies include prolonged sweating, vomiting, or diarrhea; renal disease in which sodium is reabsorbed inadequately; adrenal cortex disorders in which aldosterone secretion is insufficient to promote the reabsorption of sodium (Addison's disease); and drinking too much water. Possible effects of hyponatremia include the development of extracellular fluid that is hypotonic and promotes the movement of water into the cells by osmosis. High Na (hypernatremia): Possible causes of elevated sodium concentration include excessive water loss by evaporation and diffusion, as may occur during high fever, or increased water loss accompanying diabetes insipidus. Possible effects of hypernatremia include disturbances of the central nervous system, such as confusion, stupor, and coma. Dr. Madhukar Navgire, Jijamata College of Science and Arts, Bhende 3  BIOINORGANIC CHEMISTRY CH-342 Low K (hypokalemia): Possible causes of potassium deficiency include excessive release of aldosterone by the adrenal cortex (Cushing's syndrome), which increases renal excretion of potassium; use of diuretic drugs that promote potassium excretion; kidney disease; and prolonged vomiting or diarrhea. Possible effects of hypokalemia include muscular weakness or paralysis, respiratory difficulty, and severe cardiac disturbances, such as atrial or ventricular arrhythmias. High K (hyperkalemia):. Possible causes of elevated potassium concentration include renal disease, which decreases potassium excretion; use of drugs that promote renal conservation of potassium; insufficient secretion of aldosterone by the adrenal cortex (Addison's disease); or a shift of potassium from the intracellular fluid to the extracellular fluid, a change that accompanies an increase in hydrogen ion concentration (acidosis). Possible effects of hyperkalemia include paralysis of the skeletal muscles and severe cardiac disturbances, such as cardiac arrest. Biochemistry of Calcium and Magnesium (Ca/Mg):- Similar to Na/K; the Ca2+ ions are more concentrated to the outside of cell while Mg2+ ions are found in inside the cells. Calcium: Sparingly soluble calcium compounds (such as carbonates and phosphates) can act as bearings by being incorporated into exo- and endo-skeletons such as bone (calcium phosphate: hydroxyapatite) and sea shells (calcium carbonate: aragonite, calcite). The bones of the vertebrates are composite materials, containing about 50% collagen (a fibrous protein) and 50% hydroxyl apatite Ca5(PO4)3(OH)XF1-X (X