HORMONE SYNTHESIS, RELEASE AND TRANSPORT

The hormones speak :We are the chemical messengers of the body.Diversified in our structure and function;Act either directly or through messenger;Growth, health, and welfare is our motto

Hormone:produced in small amounts by specific tissues (endocrine glands), control the metabolic and biological activities in the target cellsHormone

HORMONE CLASSIFICATION

Protein and polypeptideAmineSteroidEicosanoid

BIOCHEMISTRY MEDICAL FACULTY USU

BIOCHEMISTRY MEDICAL FACULTY USU

PEPTIDE HORMONESConsist of specific amino acidsSynthesized as large precursor proteinsStored in membrane-enclosed compartmentsHydrophillic

PEPTIDA INSULIN

Di sintesa di Pulau Pankreas sebagai preproinsulinUntuk sekresi disimpan di RES oleh enzim mikrosomal dibelah menjadi proinsulin sewaktu memasuki membran RESProinsulin diangkut ke golgi kompleks dikemas menjadi secretory granulesDi granula, C-Peptida dipisahkan insulin disekresikan

Protein and Polypeptide Hormones Synthesis: Peptide hormone synthesis and packaging

ProinsulinInsulin

AMINE HORMONESDerived from the amino acid tyrosineIncludes thyroid hormones and catecholaminesStored until secreted

Thyroid gland produce T3 and T4 hormonesIodide (I-) actively transported into the follicle of thyroid gland Oxidized to iodine (Io) by a peroxidaseThyroid Hormones

Iodine attached to tyrosine within thyroglobulin chain MIT, DITMIT and DIT or 2 DIT molecules coupled togetherTSH via cAMP stimulates hydrolyze T3 and T4 from thyroglobulin (inhibited by KI)Thyroid Hormones

STEROID HORMONESPrecursor: CholesterolLipophillicImmediately released from the cell following synthesis

Hormon Steroid

Korteks adrenal sintesis :glukokortikoid, mineralokortikoid, sex steroidTerutama dari kolesterol plasma (sebahagian kecil dari asetil koA)Kolesterol plasma dirubah menjadi pregnenolon oleh enzim sitokrom P450 (mitkondria atau RES)

Hormon Steroid

Hormon Steroid

Kekhususan seluler :sintesis mineralokortikoid pada sel glomerulosa 18 hidroksilase dan 18 hidroksisteroid dehidrogenase hanya ditemukan pada sel ini

Golongan Hormon Steroid

Protein TransportThyroid Hormones Globulin alfa (85%)TBG TBPA (transferitin) Albumin sedikit

Protein TransportHormon Steroid

Kortisol- 75 % terikat CBG (transkortin)- 10 % kortisol bebas- selebihnya pada albumin (mis deksametason)

Protein TransportHormon Steroid

Androgen- DHEA terikat lemah pada albumin- Testoteron terikat pada globulin spesifik ( SHBG)Mineralokortikoid- tidak punya protein pengangkut spesifik- membentuk ikatan lemah dengan abumin

EICOSANOIDS HORMONEProduced from arachidonic acid, Released from phospholipids by action of phospholipase A2, phospholipase C Produced in almost every organIn one pathway arachidonic acid is converted to prostanoids by a group of enzymes, the cyclooxygenase systemA second pathway to produce leukotrienes by the enzyme 5 lipoxygenase

EICOSANOIDS HORMONE

Prostaglandins

SAIDS inhibit action of phospholipaseNSAIDs, such as aspirin and derivatives of ibuprofen, inhibit cyclooxygenase activity of PGH2 SynthaseThey inhibit formation of prostaglandins involved in fever, pain, & inflammationThey inhibit blood clotting by blocking thromboxane formation in blood platelets

REFERENCESDevlin T M, PhD. Text Book of Biochemistry with Clinical Correlations 5thed. Wiley-Liss, New York. 2002 : 906-952, 982-983McKee Trudy, McKee James R. The molecular basis of Life. 3rded. McGraw-Hill. Americas, New York. 2003 : 541-559Murray R K, et al. Harpers Biochemistry 26thed. Appleton & Lange. America 2003: 434-473Raff A, et al. Moleculer Biology of The Cell. 4thed. Garland Science. New York. 2002: 832-892Stryer L. Biokimia. Edisi 4. EGC, Jakarta. 2000.: 340-358

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