Hormone Biochemistry

7/31/2019 Hormone Biochemistry

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Hormone Signaling

A hormone is a chemical released by a cell or a gland in one part of

the body that sends out messages that affect cells in other parts of

the organism.

Hormonal signaling involves

the following:

BiosynthesisStorage and secretion

Transport to the target cell(s)

Recognition of the hormone by

receptor protein

Relay and amplification of thereceived hormonal signal

Degradation of the hormone.
http://../medical%20biochemistry/hormone/auto%20paracrine.wmv


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Endocrine System and Hormone Chemical Classes
http://../medical%20biochemistry/hormone/The%20Endocrine%20System%20-%20Part%201%20of%203%20-%20YouTube.flv


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Synthesis of Peptide and Protein Hormones

Peptide and protein

hormones are products

of translation. They vary

considerably in size

three amino acids tolarge, multisubunit

glycoproteins.

Many protein hormones

are synthesized as

prohormones.

The cell stores hormone in secretory granules and releases them in

"bursts" when stimulated . This is regulated secretion.

Alternatively, the cell does not store hormone, but secretes it from

secretory vesicles as it is synthesized constitutive secretion


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Synthesis of Steroid Hormones

Steroids are lipids and,

cholesterol. Examples include

the sex steroids such as

testosterone and adrenal

steroids such as cortisol.The first and rate-limiting step

in the synthesis of all steroid

hormones is conversion of

cholesterol to pregnenolone

Newly synthesized steroid hormones are rapidly secreted from the

cell, with little if any storage


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Synthesis of Amino Acid Derivatives

There are two groups of hormones derived from the amino acidtyrosine:

Catecholamines includeepinephrine and norepinephrine,

which are used as both hormones

and neurotransmitters

Thyroid hormones are basically a "double" tyrosine with the criticalin

corporation of 3 or 4 iodine atoms.


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The eicosanoids consist of the

prostaglandins (PGs),

thromboxanes (TXs) leukotrienes

(LTs) and Lipoxins (LXs). The PGs

and TXs are collectively identified

as prostanoids. Prostaglandins

were originally shown to besynthesized in the prostate gland,

thromboxanes from platelets

(thrombocytes) and leukotrienes

from leukocytes, hence the

derivation of their names.

Eicosanoids

Arachadonic acid is the

abundant precursor for

these hormones


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Eicosanoids exert

complex control over

many bodily systems,

mainly in inflammation

or immunity, and as

messengers in the

central nervous system.

Eicosanoids

In humans, eicosanoids are local hormones that are released by mostcells, act on that same cell or nearby cells (i.e., they are autocrine and

paracrine mediators), and then are rapidly inactivated
http://en.wikipedia.org/wiki/Inflammationhttp://en.wikipedia.org/wiki/Immune_systemhttp://en.wikipedia.org/wiki/Central_nervous_systemhttp://en.wikipedia.org/wiki/Hormonehttp://en.wikipedia.org/wiki/Autocrinehttp://en.wikipedia.org/wiki/Paracrinehttp://en.wikipedia.org/wiki/Paracrinehttp://en.wikipedia.org/wiki/Autocrinehttp://en.wikipedia.org/wiki/Hormonehttp://en.wikipedia.org/wiki/Central_nervous_systemhttp://en.wikipedia.org/wiki/Immune_systemhttp://en.wikipedia.org/wiki/Inflammation


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Synthesis of Eicosanoids

The prostaglandins are mainlymade from arachidonic acid

An enzyme attaches an

oxygen molecule to form an

endo-peroxide

Various hydrolysis reactions

then turn the peroxide into

carbonyl or hydroxyl groups,

producing one of a number of

primaryprostaglandins (e.g.

PGE2). This primarycompound is the precursor

for a whole range of other

prostaglandins
http://en.wikipedia.org/wiki/Arachidonic_acidhttp://en.wikipedia.org/wiki/Arachidonic_acidhttp://../medical%20biochemistry/hormone/Arachidonic%20Acid%20%20%20Eicosanoids%20-%20YouTube.flv


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The prostaglandins are mainly made from arachidonic acid, which

itself is synthesised in the liver from linoleic acid found in vegetable

oils. An enzyme attaches an oxygen molecule between carbon-9 and11, to form an endo-peroxide, as well as linking together carbon-8

and 12. Various hydrolysis reactions then turn the peroxide into

carbonyl or hydroxyl groups, producing one of a number ofprimary

prostaglandins (e.g. PGE2). This primary compound is the precursor

for a whole range of other prostaglandins, which are made by subtly

changing the structure or by adding or removing sidegroups.
http://en.wikipedia.org/wiki/Arachidonic_acidhttp://www.chm.bris.ac.uk/motm/linoleic/linh.htmhttp://www.chm.bris.ac.uk/motm/linoleic/linh.htmhttp://en.wikipedia.org/wiki/Arachidonic_acid


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Synthesis Ecosanoids


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Synthesis Steroid Hormones


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Peptides and Proteins

Peptide and protein hormones are, of course, products of

translation. They vary considerably in size and post-

translational modifications, ranging from peptides as short

as three amino acids to large, multisubunit glycoproteins.

Many protein hormones are synthesized as prohormones,

then proteolytically clipped to generate their mature form.

In other cases, the hormone is originally embedded within

the sequence of a larger precursor, then released by

multiple proteolytic cleavages.

Peptide hormones are synthesized in endoplasmicreticulum, transferred to the Golgi and packaged into

secretory vesicles for export. They can be secreted by one

of two pathways:

Regulated secretion: The cell stores hormone in secretory

granules and releases them in "bursts" when stimulated.

This is the most commonly used pathway and allows cells

to secrete a large amount of hormone over a short period

of time.

Constitutive secretion: The cell does not store hormone,

but secretes it from secretory vesicles as it is synthesized.

Most peptide hormones circulate unbound to other

proteins, but exceptions exist; for example, insulin-like

growth factor-1 binds to one of several binding proteins. In

general, the halflife of circulating peptide hormones is only

a few minutes.


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Amino Acid Derivatives

There are two groups of hormones derived from the amino acid

tyrosine:Thyroid hormones are basically a "double" tyrosine with the

critical incorporation of 3 or 4 iodine atoms.

Catecholamines include epinephrine and norepinephrine, which

are used as both hormones and neurotransmitters.

The pathways to synthesis of these hormones is provided in the

sections on the thyroid gland and the adrenal medulla.The circulating halflife of thyroid hormones is on the order of a

few days. They are inactivated primarily by intracellular

deiodinases. Catecholamines, on the other hand, are rapidly

degraded, with circulating halflives of only a few minutes.

Two other amino acids are used for synthesis of hormones:

Tryptophan is the precursor to serotonin and the pineal hormone

melatonin

Glutamic acidis converted to histamine
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/index.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/adrenal/medhormones.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/adrenal/medhormones.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/index.html


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