BCHM 3050 1st Edition Lecture 8 Outline of Last Lecture I Protein Structure a Primary b Secondary c Tertiary II Mutations III Protein Classification IV Torsion Angles Outline of Current Lecture I Tertiary Protein Structures II Quaternary Protein Structures III Unstructured Proteins IV Protein folding V Anfinsen Experiments VI Denaturation VII Molecular Chaperones VIII Protein Degradation IX Diseases Associated with Misfolded Proteins Current Lecture These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute I Secondary Tertiary Protein Structures a Backbone hydrogen bonds between the CO and NH b Alpha helix hydrogen bonds between every 1st and 5th i 4 c Beta sheets hydrogen bonds between sheets which line up opposite each other d Most proteins are functional when they make up a tertiary structure II Quaternary Protein Structures a Usually 4 different subunits tertiary structures interacting together as one unit and carrying out a certain function b All four subunits can be identical or completely different c RuBP Carboxylase has 10 different tertiary subunits III Unstructured Proteins a Unstructured proteins are still able to function this is very rare b Referred to as intrinsically unstructured proteins IUPs or natively unfolded proteins IV Protein folding a Protein folding can not occur on its own requires a lot of energy from the body b Ribosome are translating c Hsp70 attacks the protein initiates the process of protein with ATP ATP energy currency of the body more ATP molecules means more energy to store d ATP is broken down into ADP releasing energy to fold the protein e Folded protein handed over to Hsp60 complex GroEL barrel enzymes assist f 7 molecules of ATP are broken down and GroES is added and the lid of the barrel is shut g Folding occurs organic phosphates are released h Lid comes off and the folded protein in released V Anfinsen Experiments a Urea BME Effects i Like dissolves like inserts into peptide cavities clefts disrupts normal H bonds reforms H bonds with essentially all amino carbonyls of peptide bonds thus replacing water as H bonding partners Urea also disrupts hydrophobic interactions ii b mercapto ethanol reduces enzyme disulfides to SH b Urea breaks hydrogen bonds and breaks up the bonding between the R groups of tertiary structures c Beta mercap Breaks disulfide bridges d When the urea and beta mercap Were taken out of the mixture he noticed renaturation of the proteins occurring e Had to remove urea first the beta m to renature the protein that specific order f VI Folding procedure hydrogen bonds formed first then disulfide bonds cannot have disulfide bonds without hydrogen bonds present first Denaturation a The disruption of tertiary and secondary protein structure that leads to loss of protein function VII Molecular Chaperones a Starts at the ribosomes b Chaperones surround guide the proteins and help them to fold c Heat is one form of stress that our body is exposed to easily chaperones are trained to resist this temp heat shock proteins d Most chaperones are heat shock proteins VIII Protein Degradation a If a protein is not folded correctly it needs to be degraded b Chaperones take it to degradation chamber happens in proteasomes c 3 enzymes help to get the tag onto the protein improperly folded proteins old proteins no long needed get tagged d Ubiquitin is a functional group that tags the protein e Once it gets 4 tags the protein is guided to the proteasome to be degraded IX Diseases Associated with Misfolded Proteins a The proteins that escape the degradation machinery form plaques in the brain which are very dangerous bad b Alzheimer s Disease c Mad Cow Disease misfolded proteins do not get degraded and become plaques in the brain d CJ disease caused by the consumption of undercooked meat from mad cow diseased cows consumed the improperly folding protein which caused the normal proteins in the humans to misfold brains of the humans shrunk not genetic e Disease found amongst people in Papua New Guinea i Cannibalism eat the meat of a dead relative that dies but don t always cook it ii Contracted the disease from one of the dead relatives and people started going crazy iii Women and children contracted it more iv Prions cause misfolding of proteins f Disease found amongst people in Papua New Guinea g Cannibalism eat the meat of a dead relative that dies but don t always cook it h Contracted the disease from one of the dead relatives and people started going crazy i Women and children contracted it more j Prions cause misfolding of proteins
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