G12 sl humanbiochem

Introduction

Energy Proteins Carbohydrates Lipids Micronutrients and Macronutrients Hormones Enzymes (AHL) Nucleic Acids (AHL) Respiration (AHL)

We derive our energy from the oxidation of food Fats (37 kJ g-1) Carbohydrates CO2 + H2O + energy Proteins (17 kJ g-1)

Males have a RDI of 10500 kJ, females 8000 kJ

Lipids have a greater ratio of H:O than carbohydrates (16:1 compared to 2:1)

Use calorimeter

Natural polymers made by amino acids.

Proteins important to humans are made of 20 α-amino acids (in data booklet)

Essential amino acids: amino acids our body cannot synthesize (10)

Complete protein: a protein made of essential amino acids, e.g. casein (milk, eggs, soybeans)

Jan 3, 2010 Human Biochemistry 9


H++ H2N-CHR-COO-← H

3N+-CHR-COO- → H

3N+-CHR-COOH + OH-

>At low pH>Extra H+ reacts with OH-

>[OH- ] drops>Equilibrium shifts to the right>H

3N+-CHR-COOH form

>positive charge

>At high pH>Extra OH- reacts with H+

>[H+] drops>Equilibrium shifts to the left>H

2N-CHR-COO- form

>negative charge

>At isoelectric point>identical ionizations>only zwitterion>H

3N+-CHR-COO- form

>no net charge


H3N+-CHR-COO- + H+→ H

3N+-CHR-COOH +

H2O

>when H+ is added>equilibrium shifts to right

>[H+] drops>pH remains the same>buffer action

>when OH- is added>equilibrium shifts to left

>[OH-] drops>pH remains the same>buffer action

H2O + H

2N-CHR-COO-← OH- + H

3N+-CHR-COO-


AminoLeft

AcidRight


Primary structure>sequence of amino acids>characteristic of protein function

Secondary structure>folding of polypeptide chain>by Hydrogen bonds

α-helix: between atoms of the same chain, e.g. hair, wool

pleated sheet: between parallel chains, e.g. silk

random coil: no repeating pattern

Tertiary structure>3D shape of secondary structure> several types of interaction

Quaternary structure>3D shape of tertiary structures of different polypeptide chains


Tertiary structureMyoglobin


Quaternary structureHaemoglobin

Structural (collagen, keratin) Catalysts (enzymes) Hormones (insulin) Antibodies (interferons) Transport (haemoglobin) Energy (from muscles)



distance traveled by compounddistance traveled by solventR

f =

Rf is specific for each amino acid


H++ H2N-CHR-COO-← H

3N+-CHR-COO- → H

3N+-CHR-COOH + OH-

>At isoelectric point (pH of buffer)>identical ionizations>only zwitterion>H

3N+-CHR-COO- form

>no net charge>not affected by electric field

Different amino acids have different isoelectric points


Electrophoresis(constant pH)

G12 sl humanbiochem

Technology

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