辅酶和辅因子之间的差异

Thekey differencebetween coenzyme and cofactor is that thecoenzymes are organic molecules, whereas the cofactors can be either organic or inorganic molecules.

Enzymesare essential biological macromolecules. They are the biological催化剂, which increases the rate of biological reactions under very mild conditions. Moreover, enzymes areproteins; thus, when they are subjected to a high level of heat, salt concentrations, mechanical forces, organic solvents and concentrated acid or base solutions, they tend to denaturize. Sometimes, enzymes need the support of another molecule or an ion to have the specific function. Coenzymes and cofactors are such molecules.

内容

1.Overview and Key Difference
2.什么是辅酶
3.什么是辅助因子
4.并排比较 - 辅酶与表格形式的辅因子
5.概括

什么是辅酶？

Coenzymes are smaller organic molecules than the enzyme (which is a protein). They are mainly organic molecules, and many of them derive from vitamins. For instance, niacin produces the coenzymeNAD+that is responsible for oxidation reactions.

此外，辅酶A由泛酸制成，它们作为乙酰基载体的反应。辅酶是一种辅助因子。然而，辅酶与酶松散结合，而还有其他一些辅助因子，与酶紧密结合。

什么是辅助因子?

辅助因子是辅助化学物种（分子或离子），它与酶结合以表达酶的生物活性。大多数酶需要辅助因子来发挥其活性，而某些酶可能不需要它们。没有辅因子的酶是apoenzyme。当载酶与其辅因子在一起时，我们称其为全酶。此外，某些酶可能与一个辅因子相关，而有些酶可能与几个辅因子相关。

Without the cofactors, the enzyme activity will be lost. We can divide these molecules broadly into two groups as organic cofactors and inorganic cofactors. Inorganic ones mainly include metal ions. However, these metal ions are often needed in trace amounts. For instance, magnesium is essential for hexokinase, DNA polymerase and Glucose-6-phosphate enzymes while zinc is an essential metal ion for alcohol dehydrogenase, carbonic anhydrase and DNA polymerase function.

Significance

除镁和锌外，还有其他金属离子，例如铜，亚铁，铁，锰，镍等，它们与不同类型的酶相关。酶中的金属离子可以以三种主要方式参与催化过程。

• By binding to the substrate as to orient it properly for reaction
• And, by electrostatically stabilizing or shielding negative charges
• By facilitating oxidation, reduction reaction through reversible changes in the metal ions’ oxidation state

Moreover, organic cofactors are mainly vitamins and other non-vitamin organic molecules like ATP, glutathione, heme, CTP, coenzyme B, etc. We can divide organic cofactors further into two groups as the coenzyme and the prosthetic group. Prosthetic groups bind tightly with the enzyme and participate in the enzyme catalysis reaction. During the reaction, the enzyme- prosthetic group complex may undergo structural changes, but they are coming to the original state when the reaction is over. FAD is a prosthetic group of succinate dehydrogenase enzyme, which reduces to FADH₂in the process of converting succinate to fumarate.

辅酶和辅因子有什么区别？

A coenzyme is an organic non-protein compound that binds with an enzyme to catalyze a reaction while a cofactor is a substance (other than the substrate) whose presence is essential for the activity of an enzyme. Hence, Coenzymes are a type of cofactors. The key difference between coenzyme and cofactor is that the coenzymes are organic molecules, whereas the cofactors can be either organic or inorganic molecules.

此外，辅酶与酶松散结合，但是还有其他一些辅助因子，它们与酶紧密结合。除此之外，可以轻松从酶中除去辅酶，而辅助因子只能通过贬低酶去除辅因子。因此，这是辅酶和辅因子之间的另一个区别。

The below infographic presents the difference between coenzyme and cofactor in tabular form.

概括– Coenzyme vs Cofactor

辅酶是一种辅助因子。但是，它们之间存在差异。辅酶和辅因子之间的关键区别在于辅酶是有机分子，而辅因子可以是有机分子或无机分子。

Reference:

1. Helmenstine, Anne Marie, Ph.D. “Coenzyme Definition and Examples.” ThoughtCo, Oct. 22, 2018.Available here
2. J.H. Freeland-Graves, C. Bavik, in Encyclopedia of Food Sciences and Nutrition (Second Edition), 2003

Image Courtesy:

1.”3-methylglutaconyl coenzyme A”By Fvasconcellos. (Public Domain) viaCommons Wikimedia
2.”OSC Microbio 08 01 ApoHolo”ByCNX OpenStax(CC BY 4.0)viaCommons Wikimedia