The reaction and production of hormone from the view of biochemistry

1. HORMONAL BIOCHEMISTRY

2. Hormone
Outline
• Classification of hormone
• Properties and function of hormone
• Mechanism

3. Introduction
Hormone
- a molecule produced by specific cells that influences the
function of distant target cells. Only a small amount of
hormone is required to alter cell metabolism
- all multicellular organisms produce hormones; plant
hormones are also called phytohormones
- hormones in animals are often transported in the blood.
- endocrine hormone molecules are secreted (released) directly
into the bloodstream, while exocrine hormones (or
ectohormones) are secreted directly into a duct, and from the
duct they either flow into the bloodstream or they flow from
cell to cell by diffusion

4. Introduction
Hormone secretion

5. Introduction
- hormone secretion can be stimulated and inhibited by:
 other hormones (stimulating- or releasing-hormones)
 plasma concentrations of ions or nutrients
 neurons and mental activity
 environmental changes, e.g., of light or temperature
- hormones have the following effects on the body:
 stimulation or inhibition of growth
 mood swings
 activation or inhibition of the immune system
 regulation of metabolism

6. Introduction
 preparation of the body for fighting, fleeing, mating, and
other activity
 preparation of the body for a new phase of life, such as
puberty, parenting, and menopause
 control of the reproductive cycle
 hunger cravings
 a hormone may also regulate the production and release
of other hormones. Hormone signals control the internal
environment of the body through homeostasis

7. Hormones Classification
- vertebrate hormones fall into three chemical classes:
i. Amine-derived hormones
derivatives of the amino acids tyrosine and tryptophan.
Examples are catecholamines and thyroxine
ii. Peptide hormones
consist of chains of amino acids. Examples of small
peptide hormones are TRH and vasopressin. Examples of
protein hormones include insulin and growth hormone.
More complex protein hormones bear carbohydrate side
chains and are called glycoprotein hormones. Luteinizing
hormone, follicle-stimulating hormone and thyroid-
stimulating hormone are glycoprotein hormones.

8. Hormones Classification
iii. Lipid and phospholipid derived hormones
derive from lipids such as linoleic acid and arachidonic
acid and phospholipids. The main classes are the steroid
hormones that derive from cholesterol and the
eicosanoids. Examples of steroid hormones are
testosterone and cortisol. The adrenal cortex and the
gonads are primary sources of steroid hormones.
Examples of eicosanoids are the widely studied
prostaglandins

9. Hormones Functions
Endocrine glands

10. Hormone Functions
Source Hormone Functions
Hypothalamus Gonadotropin-releasing
hormone (GnRH) *
Corticotropin-releasing
hormone (CRH)*
Growth hormone-releasing
hormone (GHRH)*
Somatostatin*
Thyrotropin-releasing
hormone (TRH)*
Stimulates LH and FSH secretion
Stimulates ACTH secretion
Stimulates GH secretion
Inhibits GH and TSH secretion
Stimulates TSH and prolactin secretion
Pituitary Luteinizing hormone (LH)*
Follicle-stimulating
hormone (FSH)*
Corticotropin (ACTH)*
(adrenocorticotropic hormone)
Stimulates cell development and
synthesis of sex hormones in ovaries
and testes
Promotes ovulation and estrogen
synthesis in ovaries and sperm
development in testes
Stimulates steroid synthesis in adrenal
cortex

11. Hormone Functions
Source Hormone Functions
Growth hormone (GH)*
Thyrotropin (TSH)*
(thyroid-stimulating hormone)
Prolactin*
Oxytocin*
Vasopressin*
Metabolic effects in many tissues
Stimulates thyroid hormone synthesis
Stimulates milk production in mammary
glands and assist in the regulation of
the male reproductive system
Uterine contraction and milk ejection
Blood pressure and water balance
Gonads Estrogen ^
(estradiol)
Progestins ^
(progesterone)
Androgens ^
(testosterone)
Maturation and function of
reproductive system in females
Implantation of fertilized eggs and
maintenance of pregnancy
Maturation and function of
reproductive system in males
Thyroid Triiodothyronine (T3)#
Thyroxine (T4)#
(after conversion to T3)
General stimulation of many cellular
reactions

12. Hormone Functions
Source Hormone Functions
Adrenal cortex Glucocorticoids^
(cortisol, corticosterone)
Mineralcorticoids^
(aldosterone)
Diverse metabolic effects as well as
inhibiting the inflammatory response
Mineral metabolism
Gastrointestinal tract Gastrin*
Secretin*
Cholecystokinin*
Somatostatin*
Stimulates secretion of stomach acid
and pancreatic enzymes
Regulates pancreatic exocrine
secretions
Stimulates secretion of digestive
enzymes and bile
Inhibits secretion of gastrin and
glucagon
Pancreas Insulin*
Glucagon*
Somatostatin*
General anabolic effects including
glucose uptake and lipogenesis
Glycogenolysis and lipolysis
Inhibits the secretion of glucagon
* peptide or polypeptide ^ steroid # amino acid derivative

13. Hormone Action Mechanism
Steroid hormone
- steroid hormone is not water soluble. They travel in blood
attached to protein carriers
- when they arrive at the target cells, they dissociate from their
protein carriers and pass through the plasma membrane of
the cell
- some steroid hormone bind to a specific receptor proteins in
the cytoplasm and then move as a hormone-receptor
complex into the nucleus
- other steroid travel directly into the nucleus before
encountering their receptor protein

14. Hormone Action Mechanism

15. Hormone Action Mechanism

16. Hormone Action Mechanism
- the hormone receptor protein, activated by binding to the
hormone is now able to bind to specific regions of the DNA.
- these DNA region is known as the hormone response
elements
- the binding of hormone-receptor complex has a direct effect
on the level of transcription at that site.
- messenger RNA (mRNA) is produced, which then codes for
the synthesis of specific proteins

17. Hormone Action Mechanism
Non-steroid hormone
(1) Peptide hormones are transported in the
blood.
(2) They combine with receptors in the
plasma membrane of a target cell.
(3) The hormone-receptor combination is
coupled by G-protein to activate
adenylate cyclase.
(4) Cyclic AMP then activates one or more
enzymes which
(5) Phosphorylates specific cellular proteins
that
(6) alter the activity of the cell in some way.

18. Hormone Action Mechanism
Non-steroid hormone
- non-steroid hormones (water soluble) do not enter the cell
but bind to plasma membrane receptors (1st messenger)

19. Hormone Action Mechanism
- binding activates G- protein in the membrane that activates or
inhibits adenylate cyclase on the inner surface of membrane

20. Hormone Action Mechanism
- adenylate cyclase converts ATP to cAMP (2nd messenger). Ca+2,
cGMP, IP3, & DAG are also 2nd messenger types
- activation of a cAMP-dependent protein kinase called protein
kinase A
- protein kinase A is normally in an catalytically-inactive state,
but becomes active when it binds cAMP.
- upon activation, protein kinase A phosphorylates a number of
other proteins, such as enzymes that are either activated or
suppressed by being phosphorylated.
- such changes in enzymatic activity within the cell clearly alter
its state
- phosphodiesterase inactivates cAMP

21. Hormone Action Mechanism

22. Hormone Action Mechanism
Non-steroid hormone (eg. glucagon)
- glucagon binds its receptor in the plasma membrane of target
cells (e.g. hepatocytes).
- bound receptor interacts with and, through a set of G
proteins, turns on adenylate cyclase, which is also an integral
membrane protein.
- activated adenylate cyclase begins to convert ATP to cyclic
AMP, resulting in an elevated intracellular concentration of
cAMP.
- high levels of cAMP in the cytosol make it probable that
protein kinase A will be bound by cAMP and therefore
catalytically active.

23. Hormone Action Mechanism
- active protein kinase A "runs around the cell" adding
phosphates to other enzymes, thereby changing their
conformation and modulating their catalytic activity
- levels of cAMP decrease due to destruction by cAMP-
phosphodiesterase and the inactivation of adenylate cyclase.