Life and (programmed) death

I woke up yesterday feeling like I should try to get out of the house. Much to my disappointment, it stopped raining almost as soon as I stepped outside. It made me wish I had brought my umbrella, or at least one of my big hats. I saw a hawk diving for a squirrel. I rescued an earthworm. I was made aware of a music video that I was really excited about. Overall, I rejoiced at life.

The middle of my day was spent reading about death. Programmed cell death, to be specific. I had actually planned to make this a science post. It's still going to be, but my reading never crystallized into a focused topic, so this stream of consciousness shit is what you get this time.

I have been aware of a lot of the ins and outs of programmed cell death for over ten years now, starting when I took a course on the molecular biology of cancer. A major group of players in its regulation are a family of enzymes called caspases. I've known about these enzymes for years, and it wasn't until yesterday that I bothered to pay attention to why they're called "caspases."

Caspases are proteases. They break down proteins by transferring electrons to the protein's structural backbone. The caspases achieve this with cysteine, which is incorporated into their amino acid sequence. Cysteine is good at transferring electrons! But caspases are very specific about where in a protein's structure this reaction occurs. They cleave proteins specifically at the site of an aspartate amino acid. They utilize cysteine to catalyze a reaction at the site of an aspartic acid, and it acts as a protease - caspase!

I really should have picked that up years ago ... but then I might not be telling you about it right now, would I?

Here are my interesting and slightly dark thoughts for the day: 1) In the absence of a malfunction, our cells are always maintaining the infrastructure to bring about their own death. They rely on signals from their surroundings instructing them not to use it. 2) The reason interfacing with our world is bearable is because our outermost layer is dead.

That was my day yesterday. Much reading about death. One title even referred to the river Styx. Eventually my husband came home, and I took a break. He was feeling unusually adventurous, so we decided to go to a bar we've heard about but never visited before. When we got there, what do you think we found? A print of Persephone by Thomas Hart Benton on the wall!

I can't even go to a bar without it suddenly being about life and death.

Next post: Tuesday, 16 October, 2018