Bio-chemistry "Enzymes"

what is a substrate?

a reactant than an wnzyme acts on when it catalyzes a chemical reaction; they are very specific - it binds to a particular site on enzyme

what happens to the reaction rate after 40C

after 40C kinetic motion begins to unravel the enzyme and hydrogen bonds begin to break in the enzyme

how can allosteric regulation affect an enzyme?

allosteric regulation can inhibit or stimulate enzyme activity; if the enzyme is in a shape that has high affinity for its substance; or inhibits by changing the shape

recall: how do chemical reactions take place?

chemical reactions take place when bonds between reactant molecules break and rearrange to make products

what is threonine deaminase?

enzyme that allows reaction to happen and inhibits the reaction

comment on the affect of high temperatures on proteins

proteins are denatured at high temps and lose their function - devastating for the cell.

what happens to the rate of reaction as the temperature from 0-40C increases?

rate of reaction increase collisions due to kinetic energy

what is a catalyst?

substance that speeds up a chemical reaction without being consumed in the process

what happens if a cell makes too much isoleucine?

...it will combine with threonine deaminase at the allosteric site, which lowers the affinity for binding

explain how enzyme-catalyzed reactions increase in speed with an increase in temperature, what happens to the protein and enzyme?

enzyme-catalyzed reactions increase in speed with an increase in temperature; however it reaches a critical point that, then disrupts the protein structure - denaturing the enzyme

most human enzymes work best at what temperature?

37C

what is a human's normal body temperature?

37C

with your knowledge of catalysts, what are protein's catalysts?

enzymes are protein catalysts

purpose of enzymes

enzymes decrease potential energy level and thus, allow a greater proportion of colliding reactions to reach transition state and become products

when does an enzyme work its best?

every enzyme has an optimal temp at which it works its best

explain the conditions that affect enzyme activity (what happens if there's excess substrate than enzyme)

if there's excess substrate, then the rate of enzyme reactions limits the rate of reaction; e.g. when we eat cereal, too much sugar (excess substrate then enzyme) we excrete it; causing urine to smell sweet

explain the method of feedback inhibition (describe this simply)

its a method where the product of the full reaction will inhibit an enzyme at the beginning of the reaction keeping all the products "in check"

allosteric regulation

its a type of regulation in which a protein's function at one site is affected by a molecule binding to a separate site

define active site

location where substrate binds to the enzyme

what are cofactors?

nonprotein components (i.e. Zn or Mn) that are needed for some enzymes to function

what are coenzymes?

organic nonprotein cofactors (vitamins) that are needed for some enzymes to function

what are noncompetitive inhibitors?

substances that don't compete with an enzyme's substrate for the active site; they attach to another part of the enzyme and either slow the reaction or change its shape

what are competitive inhibitors?

are similar to enzyme's substrate that they are able to enter the enzyme's active site and block the normal substrate binding

describe the induced-fit model of enzyme activity

the substrate binds to the enzyme is called the active site. as the substrate enters the active site, this causes the protein to change its shape and better accommodate the substrate, which is known as the induced-fit model.

when can the transition state only be reached?

when the reactant molecules collide with enough force

can temperature affect enzyme activity? can pH affect enzyme activity?

yes both temp and pH can affect enzyme activity