Function of your protein
This protein, In order to resist these antibodies, B-Lactamase attacks the amide bonds in the antibiotics causing deacetylation to occur.
Biological relevance and broader implications
A protein with the function of being resistant to antibodies is very important to bacteria. With this protein, the bacteria can infect the host with a disease that has a very high chance of not being stopped. A protein resistant to an antibiotic used to help cure disease is never good. By studying this protein, scientists may understand why and how it is resisting antibiotics. Once, we are able to know this information, they may use it to change the antibiotics to not be resisted by B-Lactamase so we may cure diseases. The study of this protein could also factor into other antibiotics being resisted. We can use the information we find from the study of this protein and use it towards other proteins and antibiotics so all antibiotics will not be resisted.
Important amino acids
There is one important ligand in B-Lactamase. AIX or ampicillin is bonded with key amino acids of the protein; Lys73, Ser130, and Ser70. Ser130 interacts with ampicillin by hydrogen bonding. Ser70 interacts with the oxygen on the ligand. It appears to look like it is one and the same on the ligand.
Structural highlights
This protein has eight chains. In the , each of the chains has eleven alpha helixes and nine beta-sheets. To help with the stability, some of the eight chains bind to the GOL. Within each of the chains, there are two catalytic amino acids within helix number three. In helix seven is where the last catalytic acid is. These helices and beta-sheets are very important to the structure of the protein because they represent the interactions between the polypeptides. If these interactions would be changed or removed, the whole structure would change. The function of B-Lactamase would completely change.
. Inside this space-filling structure, you can see the ligand, ampicillin, as well as the hydrophobic(grey) and polar(amino acids). The tertiary structure, space-filling, allows us to view how large protein would actually appear 3-dimensionally. Inside this structure, you can spot the binding pocket where the protein would bind to the substrate. Since B-Lactamase appears to be very compact, we can assume it is very hard for solvents to pass through it or for anything to bind onto it anywhere besides the binding site.
There is no quaternary structure. Because there are not multiple molecules of the protein. If they were more than 1 molecule or strand of protein a quarternary structure would exist.
Other important features
The mechanism for Serine B-Lactamase starts with Ser70 acts as the nucleophile and is activated by a base, Glu166 via catalytic water. Cleavage of an amide bond occurs, resulting in nitrogen being protonated by Ser130 via proton shuffle from Lys73. The ending result is an acyl-enzyme intermediate. The carbonyl carbon of the intermediate is attacked by catalytic water which is activated by Glu166. Glu166 is activated by Lys73. The leaving group oxygen on Ser70 is protonated by Lys73. A hydrolyzed B-Lactam product is released to regenerate the enzyme. B-Lactamase has key active site residues. Residues Lys234 forms a hydrogen bond with Ser130 to lower the PKA to facilitate the donation of a proton to the nitrogen leaving group. Image:Https://www.pnas.org/content/117/11/5818/F1.large.jpg
The amino acids work together to lower the PKA of the entire protein. It does this so protons can be transferred from amino acids to the leaving groups. The protein does this because if it didn't it would not be able to transfer protons easily or at all. An example of this occurring is Lys234 is required for hydrolysis of cefotaxime. Lys234 provides for efficient hydrolysis of ampicillin. Lys234 forms a hydrogen bond with Ser130. The hydrogen bond and the positive charge of Lys234 would lower the PKA of Ser130 to allow the transfer of a proton from Ser130 to the leaving group nitrogen. A serine hydroxyl group PKA is 13. This means a proton from Ser130 wouldn't easily transfer a proton unless the surrounding residues didn't lower its PKA.
![[2]](https://www.pnas.org/content/117/11/5818/F1.large.jpg){kind=link}