Enzymes

The purpose of this post is to explain how our bodies produce the enzymes that are crucial in ‘enabling’ the chemical reactions that have to happen in our cells for us to function. Understanding how our cells make enzymes may not be your ‘cup of tea’ but to me it’s a fascinating tale and it’s told here to show that any advertisement that professes to improve your health by suggesting you take enzyme supplements is not to be believed.  Enzymes are proteins and your digestive system breaks them down like it would any other protein food like meat or eggs. There is one exception - for those who can’t digest milk, lactase enzyme can be taken along with dairy products.

The diagram above shows just what happens in a cell when it signals its nucleus that it needs a particular enzyme. [If ever you want to enlarge a diagram like the one above, click on it and choose x-large from the menu.] Starting at the top, a section of DNA unzips where the gene that has the instructions to make that enzyme is found, An mRNA molecule copies the sequence code, the DNA zips up again and the mRNA leaves the nucleus. The cell fluid should contain all the 20 types of amino acids and they are attracted to sites on the mRNA which in turn joins them up in the right order to make the long string enzyme protein the cell needs.

The purpose of the enzyme is shown in the diagram on the right and if you click on a simple video you will see an animated version of how it works. For reasons I'll explain below, each long string of amino acids folds up in a very specific way to create a shape on its surface that a molecule fits into - like a key in a lock.  As the molecule [or molecules] in the cell sits on the enzyme, there are interactions with it that makes a desired chemical reaction occur quickly and the product[s] leave the site so the enzyme is free to act again. When enough of the product has formed, the enzyme can be turned off by binding with competing molecules as shown in this video. 

When the mRNA is stringing together the many thousands of amino acids to make an enzyme, they're all in a line but as they hit the watery fluid in the cell, they very quickly start to fold up into an exact desired shape. The details of how this happens still puzzles scientists but there are some interesting clues. Each of the amino acids has its own properties. Some have electric charges that want to be near other charges like those in water molecules in the cell. Others have side chains that are repelled by water, like oil and water don't mix, so they have a tendency to sequester themselves on the inside of the molecule. Still others make special bridge connections. The diagram on the left gives an idea of the complexity of the folding of an enzyme molecule. Enlarging the diagram show gives you a new respect for chemists who can work out the structure of these giant molecules!! 

Our DNA has around 25,000 genes altogether and most of them code for making a specific type of enzyme protein. It is easy to understand that to stay healthy, we need to have all the amino acids available in our cells to produce enzymes. So the bottom line is: 
- be sure you are getting the proteins you need in your diet  [A couple of weeks ago I was extolling the virtues of quinoa because it is a grain that when cooked, provides all the amino acids that are needed] 
- forget about buying expensive enzyme supplements - except of course for 'lactase' if you need it. Rie

Adrenalin Kick

‘Honesty is the best policy’ Anon

I heard a story this week about a medical doctor who, out of curiosity, took a lie detector test and discovered when he looked at the printout that it had many unstable places with spiking that indicated he had lied.Puzzled, since he knew he had been totally truthful, he checked the oral recording of the questions and his answers against the results and realized that each time he had made a wisecrack he must have had an adrenalin rush to which the machine reacted.Since it was a lifelong habit of his to make witticisms at every opportunity, he realized he must be addicted to the adrenalin kicks he was getting every time.

Polygraphs or ‘lie detectors’ of one sort of another have been around since the turn of the 20^th century and are used in many countries as an aid to groups such as law enforcement agencies and employment organizations. To eliminate the problem posed by our doctor friend, only yes or no answers are demanded of the person being tested.

The test is based on the theory that when a person lies, they involuntarily release certain hormones like adrenaline from an area deep in their brain. These hormones cause the famous ‘fight or flight’ reaction that makes their heart beat faster, increases their blood pressure and breathing rate and causes them to sweat. Getting all hooked up to take the test, I think would tend to make anyone anxious and for that reason, the examiner usually poses innocuous test questions and the results are checked over with a person to be tested to create a relaxed atmosphere.  To further reassure them, the person taking the test is also made familiar ahead of time with all the questions to be asked.

I was surprised when I looked up polygraph testing on the Internet to find a number of prominent sites that can teach you how to cheat the machine and pass the tests even if you are guilty.  Since they are now no longer believed to be infallible, in most places lie detector test results are not permissible as evidence in courts. This is most unfortunate since innocent people are sometimes jailed and criminals freed because of the ease with which lies can be told in court.

Fortunately, it is possible that modern science could be coming to the rescue. As with the important forensic successes now possible using reliable DNA identification tests, 21^st century neuroscientist are working toward an infallible lie detection test. Apparently two companies are doing research using functional magnetic resonance imaging (fMRI) machines to do brain imaging to detect deception under controlled laboratory conditions.  The new ability that this machine provides to analyse what is happening inside someone’s head when they are actually telling a lie, presents serious ethical questions that will have to be sorted out in the courts before they could be used. Let us hope that in the future the threat of using these new methods will be enough to deter witnesses from lying when on the stand in court.   Rie