Text 14

Enzymes

The study of enzymes is a subject, which has a special interest because it lies just on the borderline where the biological and the physical sciences meet. On the other hand, enzymes are of supreme importance in biology. Life depends on a complex network of chemical reactions brought by specific enzymes, and any modification of the enzyme pattern may have far- reaching consequences for the living organism. On the other hand, enzymes, as catalyst, are receiving increasing attention from physical chemists.

Enzymology has become a large and rapidly developing subject, which have close connections with many sciences, especially biochemistry, physical chemistry, bacteriology and microbiology, genetics, botany and agriculture, pharmacology and toxicology, pathology, physiology, medicine, and chemical engineering. It has in addition important practical applications to activities as diverse as brewing and industrial fermentation, pest control, and chemical warfare.

It is sometimes difficult to realize that enzymology is a subject of comparatively recent growth; the beginning of the subject can be traced back to the early nineteenth century, but the great developments have come during the last forty years.

Scientists found that an alcohol precipitate of malt extract contained a thermolabile substance, which converted starch into sugar. This substance is now called "amylase".

The great increase in the knowledge of the enzymes of the living matter has brought a greatly increased understanding of the mechanism of many of the most fundamental vital processes, especially of metabolic processes which lead to the production and utilization of energy, on which life depends.

The availability of enzymes in the pure state has made possible their quantitative study by physico - chemical methods.

The substance on which an enzyme acts is termed the " substrate " of the enzyme.

In many cases an additional substance besides the enzymes and substrate is required in order that the reaction may proceed. Such " coenzymes " are part of the catalytic mechanism, and are found unchanged at the end of the reaction. They are thus distinguished from substrates.

It is frequently found that the addition of substances, which do not take part in the reaction, diminishes its velocity. These substances are known as " inhibitors ". Many of these inhibitors act as poisons of particular enzymes, and in some cases in very small concentrations.

Only comparatively recently has it been possible to develop the study of enzyme and enzyme systems in relation to the living cell.

Exercises

I. Answer the following questions:

1. Why has the study of enzymes a special interest?

2. What does life depend on?

3. What has enzymology close connections with?

4. What substance is called " amylase"?

5. What is termed the "substrate"?

6. What is a "coenzyme"?

7. What is an inhibitor?

II. Give derivatives to:

Special

Enzyme

Chemical

Modify

Rapidly

Practical

Physical activity

industry

precipitate

production

availability

pure

III. Translate into Vietnamese paying attention to the words in bold type:

1. The study of the enzymes is a subject, which has special interest.

2. The treatments to which enzymes can be subjected are limited by their instability.

3. The path of energy migration is the subject of considerable controversy.

4. When subjected to a deforming force rigid structure will often fracture.

5. Only a comparatively recent has it been possible to systematically develop the enzyme studies in relation to the living cell.

6. In many cases an additional substance besides the enzyme and substrate is required.

7. Enzymology has in addition important practical applications in brewing and industrial fermentation, pest control and chemical warfare.

8. It is frequently found that the addition of substances, which do not take part in the reaction, diminishes its velocity.

IV. Translate into English:

1. ViÖc nghiªn cøu c¸c ezim rÊt thó vÞ v× nã ë vµo giao ®iÓm cña hai ngµnh khoa häc: ho¸ häc vµ sinh häc.

2. Sù sèng phô thuéc vµo hµng lo¹t c¸c ph¶n øng ho¸ häc ®­îc th­c hiÖn nhê c¸c ezim ®Æc biÖt.

3. Enzim häc ®• trë thµnh mét ngµnh khoa häc ®ang ph¸t triÓn rÊt nhanh.

4. Sù më réng kiÕn thøc cña chóng ta vÒ ezim cña c¬ thÓ sèng ®• gióp chóng ta hiÓu râ h¬n vÒ c¬ chÕ cña nhiÕu qu¸ tr×nh c¬ b¶n.

5. ViÖc t¸ch ®­îc c¸c ezim ë d¹ng tinh khiÕt lµm cho viÖc nghiªn cøu c¸c tÝnh chÊt cña ezim trë nªn cã thÓ thùc hiÖn ®­îc.

V. Speak of the importance of enzyme