Thursday, March 29, 2012

Proteins In The Dog's Body

When I wrote about proteins in regards to nutrition, I called them the building blocks of life. Though it's not really the proteins that are the building blocks, but what they're made of, the amino acids.

If we compared amino acids to lego pieces, for example, then a protein would be an already built structure. This structure can be taken apart and the pieces used to build something else.

Example protein structure. Image
What function do proteins have in a dog's body?

Usually, when we think of nutrients, we think of structure, bricks and mortar, maybe energy. Which is true, some of the proteins in the body are structural proteins, and they can be used for energy also.

Dr. Ahern of Oregon University calls proteins workhorses. Why would he call them that?

Surely they don't actually DO things, do they? They are not like little lemmings, running around, doing stuff, are they?

Well, let's take a closer look. When your dog eats protein, how DOES it get broken down into the mentioned amino acids and how does it get put together to form proteins needed in the dog's body?

Food gets digested by the stomach acids, doesn't it? The stomach acid certainly plays its role, but it is digestive enzymes that get the job done. And guess what?

Most enzymes are proteins.

What enzymes do is nothing short of amazing. In simple terms, enzymes catalyze/speed up reactions. They are capable of speeding reactions quadrillions of times faster than they would occur otherwise.

Theoretically, these things would happen on their own ... eventually. But nobody would live that long! Digesting a chunk of meat, without enzymes, would take about 40 years! In practical terms, it's as good as if it wasn't going to happen at all. Without enzymes, life would come to a standstill.

Enzyme function schematic. Image Wikipedia

For example, when a dog's pancreas becomes unable to produce its digestive enzymes, your dog cannot digest their food and, without treatment (enzyme supplementation), would literally starve to death regardless of the amount of food they'd eat. This condition is called exocrine pancreatic insufficiency.

No enzymes, no digestion.

But enzymes don't just take things apart, they also work to put things together and have many vital functions. Enzymes deserve their own article. Bottom line, without enzymes the body could not function.

Another awesome protein is hemoglobin.

Hemoglobin molecule. Image

We all know hemoglobin, right? That's the guy that carries around oxygen and makes the blood red. But did you know that hemoglobin is a protein? And a very busy one at that. Run up to the lungs, grab oxygen, run back through the body and deliver it to the cells that need it. Grab carbon dioxide, run it back into the lungs to be expelled.

No hemoglobin, boom, you're dead.

While we're on the topic of blood, there are other proteins there with important functions.

Antibody structure. Image University of Arizona
Antibodies, anyone?

Immunoglobulins, also known as antibodies, are components of the immune system that identify and neutralize antigens, such as bacteria and viruses. Well all heard of antibodies, but did you know they are also proteins?

How about hormones?

Insulin is a good example. Insulin is a hormone produced by the pancreas, which is central to regulating blood sugar levels. When this function is disturbed, you're looking at diabetes.

There are other peptide/protein hormones, but those are not known as well.

These were just couple examples of some very cool, well-known proteins which you might have not known they are proteins.

In closing, do you want a cool example of a structural protein?

How about collagen? Yup, collagen is a protein too. Collagen is really the glue that holds the body together.

Collagen is the most abundant protein in the dog's body, and it is the main component of connective tissues. Without collagen, the body would literally fall apart.

Collagen is also a good example of the involvement of other nutrients. You all heard of scurvy? Scurvy results from vitamin C deficiency. Vitamin C is crucial to building strong collagen. Collagen is a structure formed from three strands. A healthy collagen will have these strands linked together every so often, which gives it its strength. Without going into too much detail, vitamin C is important to building these links.

Often proteins need other nutrients, such as minerals to function.

But more about these things later.

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