Saliva Protein and Enzyme Activity Lab

Vocabulary practice flashcards covering protein structures, enzymatic mechanisms, salivary functions, and quantitative biochemical assays (Bradford assay and amylase assay) from BIOL 331.

Proteins

Macromolecules composed of folded polypeptide chains that perform diverse biological functions, such as gene transcription, DNA replication, metabolism, cell cycle regulation, and immune response.

Amino Acids

The monomer building blocks that link together to form polypeptide chains.

General Amino Acid Structure

A molecular structure featuring an amino group ($-\text{NH}_2$, green), a carboxyl group ($-\text{COOH}$, yellow), and a variable side chain or R group (red) bonded to a central carbon.

R Group

The variable portion of an amino acid that confers chemical properties; polar R groups make the amino acid hydrophilic, whereas nonpolar R groups make it hydrophobic.

Protein Folding

The process governed by diverse bonds and molecular interactions (such as hydrogen bonds, disulphide bridges, ionic bonds, hydrophobic, and hydrophilic interactions) between amino acids in a peptide chain that determines protein structure and molecular interactions.

Primary Protein Structure

The fundamental linear sequence of amino acids joined together in a polypeptide chain.

Secondary Protein Structure

The local folding of the polypeptide chain into specific structural conformations, primarily $\alpha$-helices and $\beta$-pleated sheets.

Tertiary Protein Structure

The overall three-dimensional folding pattern of a protein arising from interactions between amino acid side chains (R groups).

Quaternary Protein Structure

The optional fourth structural level of a protein formed when more than one amino acid chain associates together.

Enzyme

A protein that acts as a biocatalyst to accelerate the rates of chemical reactions within living cells without being consumed.

Enzyme Activity

A metric that indicates the rate of the reaction catalyzed by a specific enzyme.

Lock and Key Model

An enzyme action model where the substrate ('key') has a shape that is perfectly complementary to the rigid active site ('key hole') of the enzyme ('lock').

Induced Fit Model

An enzyme action model where the enzyme's active site alters its conformation upon substrate binding to achieve a tight fit, resuming its relaxed conformation once the products are released.

Lock-and-Key vs. Induced-Fit Models

Two distinct mechanisms of enzyme action: one involving a pre-shaped, rigid active site complementary to the substrate, and the other involving a flexible active site that undergoes conformational changes upon substrate binding.

Enzyme Saturation

The condition reached when every active site of all available enzyme molecules is engaged with substrate, rendering further increases in substrate concentration ineffective at raising reaction rate.

Saliva

A physiological fluid composed of secretions from the parotid, submandibular, and sublingual glands containing various proteins.

Amylase

An enzyme present in saliva that catalyzes the breakdown of starch into the disaccharide maltose.

Biophotonics

The application of light-based techniques, such as spectrophotometry, to study and quantify biological molecules and systems.

Bradford Assay

A spectrophotometric procedure used to determine total protein concentration in a sample by measuring absorbance changes upon dye-protein binding.

Beer's Law

The optical principle stating that the absorbance of light by a substance in solution is directly proportional to its concentration.

Coomassie Blue Dye

A colorimetric dye that binds to the R groups of specific amino acids, turning from brown to an increasingly vibrant blue as protein concentration rises.

$$A_{595}$$

The optical absorbance measured at a wavelength of $595\,\text{nm}$, used in the Bradford assay to quantify total protein concentration based on Coomassie Blue binding.

DNSA (Dinitrosalicylic Acid)

A chemical reagent added to the amylase assay that binds to maltose and stops the starch breakdown reaction before boiling.

$$A_{540}$$

The optical absorbance measured at a wavelength of $540\,\text{nm}$, used following DNSA addition and boiling to determine the amount of maltose generated by amylase activity.

Standard Curve

A linear calibration graph generated from known concentrations of a substance plotted against absorbance to extrapolate the concentration of an unknown sample.

Molecular Weight of Maltose

The molar mass value of $342.3\,\text{g/mol}$, utilized to convert maltose concentration from $\text{g/L}$ into molarity ($\text{mol/L}$).