bchem lab: casein albumin gluten myoglobin

Milk

The most nutritionally complete food found in nature.

Whole milk

The type of milk that contains vitamins, minerals, proteins, carbohydrates, and lipids.

Lactose

The main carbohydrate present in milk.

Proteins

The nutrient group in milk that includes all essential amino acids.

Vitamins

The main _ components of milk — thiamine, riboflavin, pantothenic acid, and vitamins A, D, and K — belong to this nutrient group.

Minerals

The principal _ nutrients found in milk, such as calcium, potassium, sodium, phosphorus, and trace metals.

Lipids (fats)

The nutrient group in milk responsible for fat content.

Iron and Vitamin C

The two important nutrients in which milk is seriously deficient.

Casein

The main protein found in milk that is classified as a phosphoprotein.

Phosphoproteins

The term for proteins that have phosphate groups attached to the hydroxyl groups of some amino acid side chains.

Calcium caseinate

The form in which casein exists in milk — as a calcium salt.

At least three

The number of similar proteins that make up casein, differing mainly in molecular weight and phosphorus content.

Skimmed milk

The type of milk from which casein is typically derived.

Calcium caseinate

The calcium salt form of casein that has an isoelectric point of pH 4.6.

pH 4.6

The pH value at which calcium caseinate becomes insoluble.

pH 6.6

The approximate pH of milk, where casein has a negative charge and is solubilized as a salt.

Acid coagulation or acid precipitation of casein

The process by which adding acid to milk neutralizes the negative charges on casein micelles, causing precipitation.

Ca-caseinate + 2H⁺ → casein + Ca²⁺

The chemical reaction that describes acid-induced precipitation of casein, leaving calcium ions in solution

Calcium ions (Ca²⁺)

The ions that remain in solution after casein precipitates during acidification.

Lactic acid

The acid produced by bacterial action when milk sours, leading to clotting of casein.

Rennin

The enzyme that can clot casein, forming calcium paracaseinate which contains calcium.

Hydrolytic enzyme (peptidase)

The type of enzyme rennin is, known for cleaving peptide bonds.

Between phenylalanine and methionine residues

The specific peptide bond that rennin cleaves in casein.

Type of protein that is globular, water-soluble, and soluble in dilute salt solutions but denatured and coagulated by heat.

Albumin

Lactalbumins

The second most abundant protein type in milk, after casein.

About 41,000

The approximate molecular weight of a typical albumin molecule.

Heating to precipitate the lactalbumins

The process used to isolate lactalbumins after caseins are removed and the solution is acidified.

Maintains osmotic balance

The function of albumin that prevents fluid from leaking out of blood vessels.

Transport and nourishment functions of albumin

The general functions of albumin in the body — nourishing tissues and transporting hormones, vitamins, drugs, and substances like calcium.

ISOELECTRIC PRECIPITATION

HEAT DENATURATION

ISOLATION OF PROTEINS METHODS 2

The pH value at which a protein has zero net charge.

The pH value at which a protein has zero net charge.

Isoelectric precipitation

The isolation method that involves adjusting the pH of a protein source until the isoelectric pH is reached, causing precipitation.

pH 4.6

The isoelectric pH value for casein, at which it precipitates from skimmed milk.

They have zero net charge and can no longer interact with other components

The reason proteins become insoluble and precipitate at their isoelectric pH.

Casein

The protein commonly isolated by isoelectric precipitation from skimmed milk.

Heat denaturation

The isolation method that involves disrupting the secondary and tertiary structure of proteins without breaking peptide bonds.

Hydrogen bonds and nonpolar hydrophobic interactions

The type of bonds disrupted during protein heat denaturation.

Primary structure (amino acid sequence)

The level of protein structure that remains intact after heat denaturation.

Albumin

The protein that can be isolated from skimmed milk using heat denaturation.

Gluten

A mixture of two proteins, glutenin and gliadin, found in wheat flour.

Glutenin and gliadin

The two main protein components of gluten.

Prolamin–glutelin composite

The type of protein composite that gluten represents, consisting of a prolamin and a glutelin.

Endosperm

The part of the grain where gluten exists conjoined with starch

30%

The approximate percentage of gliadins in total wheat grain protein.

50%

The approximate percentage of glutenin in total wheat grain protein.

Glutamine and proline

The amino acids that are abundant in gliadins and make them capable of triggering immune responses in celiac disease.

Celiac disease

The disease caused by immune response to certain protein sequences (epitopes) in gliadin.

Gliadin

A type of gluten protein that is insoluble in water and found in wheat and other cereals of the genus Triticum.

Gliadin

The gluten component essential for giving bread its ability to rise during baking

Glutenin

A type of gluten protein that is insoluble in water and made up of high and low molecular mass subunits.

Glutenin

The gluten component responsible for the strength and elasticity of dough made from wheat flour.

Gliadin and glutenin

The two main protein components that together form gluten in wheat flour.

Gluten

A yellowish-white, tough, elastic, and sticky protein found in wheat that gives bread its structure.

Carbon dioxide (CO₂)

The reason gluten is useful in bread making — it traps this gas produced by flour and yeast reaction.

Chewiness and shape retention

The characteristic texture that gluten provides to baked bread.

Gluten isolation from wheat flour

The process of isolating gluten by soaking wheat grains and washing or kneading to remove starch.

Insoluble protein fraction (raw gluten)

The part of wheat that remains insoluble and constitutes raw gluten.

Sensitivity to temperature

The property of gluten that makes it difficult to obtain in dry form.

Difference in solubility

The main principle involved in the isolation of gluten from wheat flour.

Starch

The component of wheat that is partially soluble in water.

Gluten

The component of wheat that is insoluble in water.

Washing with water

The method used to separate gluten from starch.

Iodine solution

The reagent used to test for the complete removal of starch during gluten isolation.

Blue-black

The color of the positive complex formed when iodine reacts with starch.

Iodo-starch complex (blue-iodo-starch complex with triiodide)

The specific complex formed between iodine and starch that gives a blue-black color.

Myoglobin

A member of the globin superfamily protein found mainly in vertebrate striated muscles.

Myoglobin

The protein responsible for the red color of muscles in most vertebrates.

Striated muscle

The type of muscle where myoglobin is most abundant.

Nitric oxide

The molecule that myoglobin helps regulate as part of its role in hemostasis.

Detoxification of reactive oxygen species

The role of myoglobin in protecting cells from reactive oxygen species

During hypoxia or anoxia

The condition under which myoglobin releases its stored oxygen to the body.

Oxygen storage and release in muscle tissues

The general function of myoglobin related to oxygen.

Differential solubility, centrifugation, and protein purification

The main principle involved in isolating myoglobin from beef muscle. 3

To extract and concentrate the oxygen-binding protein

The general purpose of isolating myoglobin from muscle tissue.

Myoglobin

The protein extracted from beef muscle that binds and stores oxygen.

Tissue Homogenization

Method used to break down muscle cells to release intracellular contents.

Break down muscle cells to release intracellular contents

Principle of tissue homogenization.

To maintain protein stability and prevent degradation

During tissue homogenization, why is cold phosphate buffer used?

Differential Solubility

Method based on myoglobin’s water solubility to separate it from insoluble debris.

Myoglobin is water-soluble

Principle of differential solubility in myoglobin isolation.

Filtration or centrifugation

Step used to remove insoluble debris and keep myoglobin in the supernatant.

Centrifugation

Method used to separate soluble proteins from cell debris.

Separate soluble proteins from cell debris

Principle of centrifugation in myoglobin isolation.

Ammonium sulfate precipitation

Method used to concentrate myoglobin and remove contaminants by salting out proteins.

Proteins precipitate at different salt concentrations

Principle behind ammonium sulfate precipitation.