Proteins

involved in EVERYTHING! – structural AND functional (enzymes = most important) tens of thousands of different proteins – each has a specific shape and function HUGE polymers – created from just 20 amino acids (monomers) © 2012 Pearson Education, Inc.

Structural proteins provide associations between body parts. Contractile proteins are found within muscle. Defensive proteins include antibodies of the immune system. Signal proteins are best exemplified by hormones and other chemical messengers. Receptor proteins transmit signals into cells. Transport proteins carry oxygen. Storage proteins serve as a source of amino acids for developing embryos. © 2012 Pearson Education, Inc.

Proteins: commonalities

Proteins: differences based on R groups hydrophobic (non-polar) hydrophilic (polar)

Proteins: creation aa monomers are linked together through: dehydration synthesis create a peptide bond = dipeptide (etc.) = polypeptide

Proteins: structure Primary: aa sequence (aa used + order they’re in) Secondary: hydrogen bond interactions (between N-C-C backbones of aa) Tertiary: R group interactions (hydrogen bonds + covalent bonds) Quarternary: (not all proteins) individual subunits put together to make a larger unit © 2012 Pearson Education, Inc.

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n_folding.htm

Denatured protein Native protein

Enzymes biological catalysts: cause rxns to happen faster than they normally would rxns would happen anyway-just not at the speed necessary for life cause reaction to happen but are not altered by the rxn shaped based: specific enzymes cause specific reactions

Enzymes substrate + enzyme → product Enzyme Enzyme–substrate complex Product Enzyme Active site

Figure 5.13A_1 Activation energy barrier Reactant Products Without enzyme Energy

Figure 5.13A_2 Activation energy barrier reduced by enzyme Reactant Products With enzyme Energy Enzyme

Figure 5.14_s1 1 Enzyme (sucrase) Active site Enzyme available with empty active site

Figure 5.14_s2 2 1 Enzyme (sucrase) Active site Enzyme available with empty active site Substrate (sucrose) Substrate binds to enzyme with induced fit

Figure 5.14_s Enzyme (sucrase) Active site Enzyme available with empty active site Substrate (sucrose) Substrate binds to enzyme with induced fit Substrate is converted to products H2OH2O

Figure 5.14_s Products are released Fructose Glucose Enzyme (sucrase) Active site Enzyme available with empty active site Substrate (sucrose) Substrate binds to enzyme with induced fit Substrate is converted to products H2OH2O

Rate of Reaction temperature pH cofactors (coenzyme if organic) competitive inhibitors – block active site noncompetitive inhibitors – Δ shape of enzyme = non-fxnal active site

Figure 5.15A Substrate Enzyme Allosteric site Active site Normal binding of substrate Competitive inhibitor Noncompetitive inhibitor Enzyme inhibition

Reaction with enzyme Maximum rate Reaction without enzyme

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