Download Pharos university Faculty of Allied Medical SCIENCE Biochemistry 1

Dr. Tarek El Sewedy
Department of Medical Laboratory Technology
Faculty of Allied Medical Sciences
Amino acids and proteins
Part 2
INTENDED LEARNING OUTCOMES
By the end of this lecture, students will learn:
1.
Amino Acids classification.
LECTURE CONTENT
• Classification of amino acids
• Amino Acids and proteins nutritional facts
•
The basic structure of an amino-acid molecule consists of a carbon atom
bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen
atom, and a fourth group that differs from one amino acid to another and
often is referred to as the-R group or the side chain.
•
The-R group, which can vary widely, is responsible for the differences in
chemical properties.
α, β, or γ Amino Acids
 Amino acids may be characterized
as α, β , or γ
depending on the location of the
amino group on the carbon chain.
 α are on the carbon adjacent to
the carboxyl group.
 β are on the 2nd carbon
 γ on the 3rd carbon from the
carboxyl group.
α− amino acids
 Amino acids found in proteins are α− amino acids.
 The amino group is always found on the carbon adjacent
to the carboxyl group
Metabolic Classification of the Amino Acids
 Essential and Non-essential
 Glucogenic and Ketogenic
Essential Amino Acids
 Only 11 Of the 20 amino acids that make up proteins can
be synthesized by the human body
 The other 9 amino acids must be acquired from food
sources. These amino acids are known as essential
amino acids
Non essential Amino Acids
Glucogenic or ketogenic Amino acids
 Glucogenic amino acids are
degraded to compounds that can
be used as carbon skeletons for
glucose synthesis via
gluconeogenesis.
 Ketogenic amino acids are
degraded to compounds that can
only be used to generate the
ketone bodies.
Glucogenic Amino Acids
Ketogenic Amino Acids
 Metabolized to acetyl CoA or acetoacetyl CoA then
to ketone bodies
 Leucine
 Lysine
Amino Acid Functions
1. Amino acids are
the building
blocks of proteins.
2. Some amino acids and
their
derivatives function as
neurotransmitters hormones.
3. It may supply the
carbohydrates pool with
glucose ?????????.
Protein functions
1.
- Catalytic functions [enzymes]
2. - Receptor [insulin receptor]
3. - Structural function [collagen]
4. - Transport [hemoglobin]
5. - Protective functions [Antibodies]
Protein function (cont…)
6. - Hemostasis [clotting factors]
7. - Hormonal functions [insulin, glucagon, GH]
8. - Control of gene expression [transcription factors]
9. - DNA packing [histones]
10. - Act as buffers.
Protein nutritional facts
Spirulina
quinoa
soybeans
Almond
Good sources of protein
Amino Acid nutrition
Our body doesn’t use proteins in a direct way; first proteins are decomposed into amino
acids and then amino acids are used for the resynthesize of muscular proteins
Protein and diet
Protein and diet
•
An individual's daily protein requirement depends on several factors, including:
1.
Age - a growing child's needs will not be the same as an individual aged 80 years
2.
Sex - males generally require more protein than (non-pregnant or non-breastfeeding) females
3.
Weight - an individual who weighs 100 Kg will require more protein compared to somebody who
weighs 50 Kg.
4.
Muscular exertion - an individual who earns his living delivering pianos will require more protein
than a computer programmer of the same age and height.
5.
Muscle mass - a muscle-bound weight trainer will need more dietary protein than a marathon runner
6.
Health - a person who is recovering after an illness or medical procedure may need more dietary
protein than other people.
• Percentage of energy that should come from protein:
• Children aged 1 to 3 years - 5% to 20%
• Children aged 4 to 18 years - 10% to 30%
• Adults - 10% to 35%
• According to the US Department of Agriculture, our protein intake should be:
• Infants - 10 grams per day
• Teenage boys - up to 52 grams per day
• Teenage girls - up to 46 grams per day
• Adult men- approximately 56 grams per day
• Adult women - approximately 46 grams per day
• Pregnant or lactating (breastfeeding) women - about 71 grams per day
Protein deficiency
 Mental retardation and reduced IQ.
 Growth problems
 Wasting and shrinkage of muscle tissue
 Apathy
 Swollen belly
 Anemia
 Weaker immune system
Protein Excess
 Weight gain.
 Intestinal irritation.
 Risk of heart disease
 Kidney problems
 Gout disease
‫أالء صالح الخضري‬
ASSIGNMENTS
• Selected students are requested to prepare slides about one of the
following topics (To be delivered before next lecture):
• Digestion of proteins
• Essential amino acids.
• Non essential amino acids
• Physical properties of amino acids.
• Chemical properties of amino acids.
• Disease resulting from disturbance in amino acid metabolism.
• Ketone bodies and amino acids
• Translation of RNA
Study Question
 Write three points about :
Classification of amino acids
 1 2 3-
Suggested readings:
Principles of Biochemistry, Donald J. Voet, Judith G.
Voet, Charlotte W. pratt; Willey, 3rd ed.