Sept 10 - Biochem 423 Robert A Orlando Ph.D ENZYMES –...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Biochem 423 Robert A. Orlando, Ph.D. ENZYMES – KINETICS EXAMPLE FROM MARKS’ Metabolic pathways will proceed to their ends if exergonic A → B → C → D → E Need to regulate to control metabolic events. Cars = pathway intermediates Barrier slows pathway = to rate limiting enzyme Some take alternate exit (branch points in pathway). TWO MAJOR WAYS TO REGULATE ENZYME ACTIVITY: PHYSICAL INHIBITOR – MORE ON THIS LATER LIMIT SUBSTRATE 49 | P a g e Biochem 423 Robert A. Orlando, Ph.D. EFFECTS OF [SUBSTRATE] ON ENZYME ACTIVITY Product formation X X INTERPRETATION OF THIS GRAPH: k1 k2 E + S → ES → E + P ← ← k−1 k−2 k1 >>>> k2 SO “BARRIER” IS AT k2 AND [ES] BACKS UP IF NO “BARRIER” WAS PRESENT AT k2 THEN GRAPH WOULD BE LINEAR 50 | P a g e Biochem 423 Robert A. Orlando, Ph.D. THEREFORE VO = k2[ES] (RATE OF ES → P) AND VMAX OCCURS WHEN ENZYME IS SATURATED ALGEBRAIC EQUATION DESCRIBING THIS GRAPH: MICHAELIS‐MENTEN VO = VMAX [S] Km + [S] ....SO WHAT IS Km (MICHAELIS CONSTANT) Km = ½ VMAX PERMITS COMPARISON OF ACTIVITIES BETWEEN ENZYMES HIGH Km = LOW BINDING AFFINITY LOW Km = HIGH BINDING AFFINITY 51 | P a g e Biochem 423 Robert A. Orlando, Ph.D. BECAUSE CURVE IS HYPERBOLIC, CANNOT ACCURATELY DEFINE VMAX OR KM…. ALGEBRAIC TRANSFORMATION OF MICHAELIS‐MENTEN EQUATION: DOUBLE‐RECIPROCAL PLOT (LINEWEAVER‐BURK PLOT) VO = VMAX [S] Km + [S] → 1 = Km + [S] VO VMAX [S] SEPARATE NUMERATORS 1 = Km + [S] VO VMAX [S] → 1 = Km + [S] . VO VMAX [S] VMAX [S] SIMPLIFY (REMOVE [S]) 1 = Km + 1 VO VMAX [S] VMAX WHERE → FORM y = mx + b y = 1 x = 1 b (y‐intercept) = 1 . VO [S] VMAX 52 | P a g e Biochem 423 Robert A. Orlando, Ph.D. LINEWEAVER‐BURK PLOT WHEN y = 0, solve for x 53 | P a g e ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern