Question

which of the following enzyme is not helpful to remove free radicals in reperfusion injury?
a) lipid peroxidase
b) superoxide dismutase(sod)
c) catalase
d) glutathione peroxidase ​

Answer 1

In recent years, there has been a great deal of attention toward the field of free radical chemistry. Free radicals reactive oxygen species and reactive nitrogen species are generated by our body by various endogenous systems, exposure to different physiochemical conditions or pathological states. A balance between free radicals and antioxidants is necessary for proper physiological function. If free radicals overwhelm the body's ability to regulate them, a condition known as oxidative stress ensues. Free radicals thus adversely alter lipids, proteins, and DNA and trigger a number of human diseases. Hence application of external source of antioxidants can assist in coping this oxidative stress. Synthetic antioxidants such as butylated hydroxytoluene and butylated hydroxyanisole have recently been reported to be dangerous for human health. Thus, the search for effective, nontoxic natural compounds with antioxidative activity has been intensified in recent years. The present review provides a brief overview on oxidative stress mediated cellular damages and role of dietary antioxidants as functional foods in the management of human diseases.

Keywords: Ageing, antioxidant, free radicals, oxidative stress

INTRODUCTION

The recent growth in the knowledge of free radicals and reactive oxygen species (ROS) in biology is producing a medical revolution that promises a new age of health and disease management.[1] It is ironic that oxygen, an element indispensable for life,[2] under certain situations has deleterious effects on the human body.[3] Most of the potentially harmful effects of oxygen are due to the formation and activity of a number of chemical compounds, known as ROS, which have a tendency to donate oxygen to other substances. Free radicals and antioxidants have become commonly used terms in modern discussions of disease mechanisms.

Answer 2

Answer:

The correct answer to the question which of the following enzymes is not helpful to remove free radicals in reperfusion injury is a) lipid peroxidase.

Explanation:

• Reperfusion injury refers to cytotoxic damage due to oxidative stress as a result of release of free radicals when a tissue regains its blood perfusion after a period of ischemia.
• Free radicals are those compounds which contain an odd number of electron and are highly reactive as they wish to complete the electron pair for stability.
• They oxidise those tissues which they come across by extracting electrons and, in turn, set up a chain reaction of formation of free radicals.
• The tissues inside the body contain free radical scavengers which reduce the free radicals and terminate the chain reaction of formation of free radicals.
• These free radical scavengers are Superoxide dismutase (reducing superoxide free radical), Catalase and glutathione peroxidase (reducing peroxide free radicals).
• The enzyme lipid peroxidase forms peroxide ions which in turn generate peroxide free radicals.

Hence, the enzyme lipid peroxidase is not a free radical scavenger, rather, it generates peroxide free radicals in peroxisomes.