NOTE4 LU4 Amino Acid and Protein

Learning Unit 4: Amino Acid & Protein

Preparation and Contributors

Course Code: ASH10303 and ASQ10103
Title: Fundamental Biochemistry in Animal Sciences
Prepared by: Dr. Grace Nguang Siew Ing
Edited and presented by: Dr. Fathurrahman Lananan

Section A: Overview of Amino Acids & Protein

Learning Outcome
- Explain the principles of amino acids & proteins and their metabolisms.
- Suggest techniques for applying animal sciences using principles of biochemistry.
- Handle experiments using basic laboratory equipment.
- Analyze results and correlate them to biochemistry theory.
Introduction of Amino Acids & Proteins
- What is Protein?
  - Proteins are organic nitrogenous compounds consisting of Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).
  - They are polymers formed from 20 naturally occurring amino acids.
  - Amino acids are organic acids where one hydrogen atom is replaced by an amino group (NH3), typically at the alpha (α) carbon adjacent to the carboxyl (-COOH) group.
- General Structure of an Amino Acid
  - Each amino acid (except proline) contains:
  - A carboxyl group (-COOH)
  - An amino group (-NH2)
  - A unique side chain bonded to the alpha carbon
  - At physiological pH (7), the carboxyl group dissociates, forming a negatively charged carboxylate ion (-COO-) and the amino group is protonated (-NH3+).
- Types of Amino Acids
  - Non-Polar Amino Acids: Glycine (Gly, G), Alanine (Ala, A), Valine (Val, V), Cysteine (Cys, C), Proline (Pro, P), etc.
  - Charged Amino Acids: Lysine (Lys, K), Arginine (Arg, R), Histidine (His, H).
  - Polar Amino Acids: Serine (Ser, S), Threonine (Thr, T), Tyrosine (Tyr, Y), Asparagine (Asn, N), Glutamine (Gln, Q), etc.
Importance of Amino Acids & Proteins
1. Repair & Maintenance
  - Proteins are essential for building and maintaining body tissues, including hair, skin, muscles, and organs.
  - Keratin, a protein, is crucial for skin, hair, and nails.
  - Children require more protein per pound of body weight for growth compared to adults.
2. Energy Source
  - Proteins serve as a major energy source, especially when consumed in excess of bodily needs.
  - Excess protein is converted to fat if not required for tissue maintenance.
  - Adult horses typically require 8-10% protein in their diet; however, lactating mares and growing foals need more.
3. Hormones
  - Proteins are crucial in the synthesis of hormones that regulate body functions.
  - Example: Insulin regulates blood sugar levels by facilitating interaction between the pancreas and liver.
  - Another example is Secretin, which stimulates the pancreas and intestines for digestion.
4. Enzymatic Activity
  - Enzymes, which are proteins, catalyze chemical reactions necessary for life.
  - Various enzymes assist in breaking down macromolecules or synthesizing DNA.
5. Transport and Storage
  - Proteins are involved in the transport of molecules, exemplified by hemoglobin transporting oxygen in the body.
  - Certain proteins also play a role in storing molecules, such as ferritin storing iron in the liver.
6. Antibody Formation
  - Proteins also form antibodies that protect against infections and diseases by identifying and neutralizing pathogens.
  - Antibodies work alongside immune system cells to encase and destroy antigens such as bacteria and viruses.
7. General Importance
  - Proteins are vital across all animal species—horses, dogs, cats, fish, etc.
  - They support skeletal and muscular systems, organ function, nervous system health, immune responses, and more.
  - Adequate protein intake is critical for effective reactions to infections.
Plant-Based Proteins
- Misconceptions exist regarding the importance of protein for herbivorous animals.
- Multiple plant-based amino acids sources exist—e.g., Malabar spinach, seaweed, and beans.
- Careful selection of protein sources based on individual dietary needs is essential.
Malnutrition Indicators
- Signs of nutrient deficiencies can include severe dermatitis, poor growth, hair loss, and leg deformities in various species.

Section B: Amino Acid & Protein Metabolism

Classification of Amino Acids

By Structure
- Aliphatic: No ring structure.
- Aromatic: Contains benzene/phenol rings.
- Heterocyclic: Contains additional ring structures.
By Polarity
- Polar: Charged (e.g., Aspartic Acid, Glutamic Acid) and uncharged (e.g., Serine, Threonine).
- Non-Polar: Hydrophobic amino acids (e.g., Alanine, Leucine).
Optical Activity
- All amino acids are optically active and may exhibit D & L isomerism, except for Glycine, which is not optically active as it lacks an asymmetric alpha carbon.
Nutritional Value
- Essential Amino Acids: Cannot be synthesized by the body; must be ingested (e.g., Valine, Leucine).
- Non-Essential Amino Acids: Can be synthesized but may be insufficient during periods of growth (e.g., Arginine, Histidine).
- Semi-Essential Amino Acids: Cannot be synthesized adequately in certain life stages (e.g., Arginine during growth).

Metabolic Fate of Amino Acids

Amino acids can be classified based on their metabolic fate as glucogenic or ketogenic.

Glucogenic Amino Acids: Can be converted into glucose (e.g., Glycine, Serine).
Ketogenic Amino Acids: Can be converted into ketone bodies and fat (e.g., Leucine, Lysine).
Mixed Amino Acids: Can yield both glucose and ketone bodies (e.g., Isoleucine, Tyrosine).

Special Functions of Amino Acids

Specific amino acids can have unique roles in biochemical processes, such as protein synthesis, metabolic regulation, immune responses, and nutrient transport.

Synthesis and Classification of Proteins

Structure: Depends on the arrangement of amino acids and their interactions (e.g., primary, secondary, tertiary, and quaternary structures).
Denaturation and Conformation: Altering protein shape affects function.

Conclusion

The overall significance of amino acids and proteins in nutrition, metabolism, and their diverse physiological roles in animal health is pivotal. Understanding these components can aid in improving animal welfare and management practices in various species.

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Definition Compilation: Amino Acids & Proteins

Proteins: Organic nitrogenous compounds consisting of Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N). They are polymers formed from 20 naturally occurring amino acids.
Amino acids: Organic acids where one hydrogen atom is replaced by an amino group ( $NH3$ ), typically at the alpha ( $\alpha$ ) carbon adjacent to the carboxyl ( $-COOH$ ) group.
Enzymes: Proteins that catalyze chemical reactions necessary for life.
Antibodies: Proteins that protect against infections and diseases by identifying and neutralizing pathogens.
Aliphatic amino acids: Amino acids with no ring structure.
Aromatic amino acids: Amino acids containing benzene/phenol rings.
Heterocyclic amino acids: Amino acids containing additional ring structures.
Polar amino acids: Amino acids that are charged (e.g., Aspartic Acid, Glutamic Acid) and uncharged (e.g., Serine, Threonine).
Non-Polar amino acids: Hydrophobic amino acids (e.g., Alanine, Leucine).
Optical Activity (Amino Acids): The property where amino acids, except Glycine, exhibit D & L isomerism due to having an asymmetric alpha carbon.
Essential Amino Acids: Cannot be synthesized by the body; must be ingested (e.g., Valine, Leucine).
Non-Essential Amino Acids: Can be synthesized but may be insufficient during periods of growth (e.g., Arginine, Histidine).
Semi-Essential Amino Acids: Cannot be synthesized adequately in certain life stages (e.g., Arginine during growth).
Glucogenic Amino Acids: Amino acids that can be converted into glucose (e.g., Glycine, Serine).
Ketogenic Amino Acids: Amino acids that can be converted into ketone bodies and fat (e.g., Leucine, Lysine).
Mixed Amino Acids: Amino acids that can yield both glucose and ketone bodies (e.g., Isoleucine, Tyrosine).
Protein Structure: Depends on the arrangement of amino acids and their interactions (e.g., primary, secondary, tertiary, and quaternary structures).
Denaturation and Conformation (Protein): Altering protein shape, which affects its function.