Download
1 / 55
580 likes | 1.02k Views
Cap 3 – Energía, Catálisis y Biosíntesis. JA Carde, PhD Universidad Adventista Alberts et al. Enzimas. 03_01_A series of enzyme.jpg. 03_02_metabolic pathways.jpg. 03_03_Catabolic anabolic.jpg. 03_04_Biological structur.jpg. Estructuras biológicas: orden. Entropía espontánea diaria.
E N D
Cap 3 – Energía, Catálisis y Biosíntesis JA Carde, PhD Universidad Adventista Alberts et al.
Enzimas 03_01_A series of enzyme.jpg
03_04_Biological structur.jpg Estructuras biológicas: orden
Entropía espontánea diaria 03_05_Toward disorder.jpg
Oxidacion: perdida de e-; que se traduce en 03_12_Oxidation reduction.jpg Disminucion en los enlaces C-H
03_13_activation energy.jpg Enzimas: ayudan en la célula a empujar las reacciones por sobre la E de activacion
Mientras mas E por molecula menos moleculas tienen esa energia!!! 03_14_Lowering activation.jpg La presencia de una Enzima hace que un Numero mayor de moleculas tengan la energia para que la reaccion proceda!!!
03_15_Enzymes catalyze.jpg Selectivas: catalizan una reaccion especifica Rutas especificas: una serie de enzimas presentes determina la ruta metabolica que una molecula X seguira; esto implica: CONTROL Hay una enzima presente PLT…
Sitio Activo: region en la enzima con caracteristicas unicas para una molecula unica o sea su sutrato. 03_16_Enzymes convert.jpg Participan en la reaccion PERO no son alteradas o afectadas.
Reacciones E favorables: crean desorden pq disminuyen la E libre del sistema PLT tienen ΔG negativo Reacciones E desfavorables: crean orden pq aumentan la E libre del sistema PLT tienen AG positivo
Entonces una reacciónYX va deYX ; si tiene ΔG-o va deYX; si tiene ΔG+
Que factores afectan ΔG de una reacción?- la energía almacenada en cada molécula (potencial químico)- las concentraciones de las moléculas en la mezclaEj: un exceso de Y sobre X favorece laYX, pq habrá mas moléculas haciendo esa transición PLT el ΔG será mas negativo también
Como yo puedo determinar cuanta diferencia en [ ] se necesita para compensar una disminución en energía química?Con un análisis termodinámico, donde se separa la parte del cambio de energía libre que es dependiente de [ ] de la parte que es independiente de [ ] .
*ΔG= AGo+ 0.616 ln [X]/[Y] • Δgo - depende de las característica intrínsecas de las moléculas (en condiciones ideales) • +… dependiente de las concentraciones • * para una reacción YX , 37oC • ΔG – Kcal/mol • [Y] y [X] – concentraciones de estos • RT = 0.616 constante y ln log natural
*ΔG= AGo+ 0.616 ln [X]/[Y] • Si las concentraciones de X y Y son 1M; Que pasa con la relación entre ΔG y AGo ? • Si la razón X:Y disminuye, ΔG sera mas negativo, PQ? • Cuando la velocidad de ambas reacciones es igual se llega al equilibrio qumico: estado en el que la razon de X y Y se mantiene constante; • K = [X]/[Y]; donde K es la constante de equilibrio; • punto donde el efecto de las concentraciones balancea el empuje dado a la reaccion por el ΔG, • PLT no hay cambio en energia libre que empuje la reacción hacia ningun lado asi que AG = 0
Relacion entre K y G 03_20_binding interactions.jpg
Inhibidores • Inhibitors are compounds which interact with an enzyme to slow down its rate of reaction • Many toxic compounds are enzyme inhibitors, being toxic because they inhibit enzymes responsible for vital reactions. • Inhibitors can interact with an enzyme in different ways and enzyme kinetics is a major tool in distinguishing between these mechanisms.
Inhibicion Competitiva • In the presence of a competitive inhibitor the enzyme can bind • to the substrate: to form an enzyme-substrate complex, • or the inhibitor: to form an enzyme-inhibitor complex.
Inhibicion Competitiva • Competitive inhibitors prevent the substrate from binding to the enzyme and thereby prevent the enzyme from converting it to product. • They are mutually exclusive with the substrate so prior binding of the substrate prevents the inhibitor from binding. • Consequently competitive inhibitors are inactive at very high substrate concentrations and do not therefore alter the maximal velocity. • They are active at low substrate concentrations which is seen as an increase in the slope of the Lineweaver-Burk plot. • They reduce the affinity of the enzyme for its substrate; seen as an increase in the Michaelis constant.
Inhibicion Competitiva • Effects on Km • Kmis an indication of enzyme-substrate affinity. • In the presence of a competitive inhibitor some enzyme molecules will exist as free enzymes, others as enzyme-inhibitor complexes. So a competitive inhibitor reduces enzyme-substrate affinity, or increases Km. • Effects on Vmax • Vmaxis the velocity at very high substrate concentration. • Under these conditions the inhibitor is competed out by the substrate and does not inhibit the enzyme at all. So competitive inhibitors do not slow the reaction at high substrate concentrations and then is no change in Vmax.
Inhibicion NO-Competitiva • A noncompetitive inhibitor binds to an inhibitor site on the enzyme which is remote from the active site and brings about a conformational change in the active site. • In this sense it's very similar to one of the competitive inhibitor types. • The difference is that this time the change in the active site is such that it does not prevent substrate binding but, rather, prevents the enzyme from converting the bound substrate to product.
Inhibicion NO-Competitiva Effects on Km A classical noncompetitive inhibitor has no effect whatsoever on substrate binding so the enzyme-substrate affinity, and hence the Km, are unchanged. Effects on Vmax Noncompetitive, of both the classical and mixed varieties, inhibit at high substrate concentrations so the Vmax is decreased.
Inhibicion DE-Competitiva Probably the main claim to fame of uncompetitive inhibitors is the frequent confusion of names between them and noncompetitive inhibitors! The key feature of these inhibitors is they are incapable of binding to free enzyme.
Inhibicion DE-Competitiva • They can only bind to the enzyme-substrate complex. • This could be because the substrate is itself directly involved in binding the inhibitor or because it brings about a conformational change in an inhibitor binding site which was previously incapable of binding the inhibitor. • Once the inhibitor has bound it prevents the enzyme from turning the substrate into product. Again this could be some kind of direct interaction, or due to a change in conformation of the active site.
