Amino Acids
The side chain of this amino acid has a pKa of 6.0 and commonly exists in both the protonated and deprotonated forms under physiological conditions.
What is histidine?
The tendency of hydrophobic resdues to be buried in the interior of a water-soluble globular protein is a result of this biochemical phenomenon.
What is the hydrophobic effect?
This type of catalysis involves the formation of a transient covalent bond between a reactive group of the enzyme and the substrate.
What is covalent catalysis?
These two purines are found in DNA and RNA, where they base pair with pyrimidines to stabilize the structure of nucleic acids.
What are adenine and guanine?
This class of lipids is a major component of fats and consists of a glycerol backbone esterified to three fatty acids residues.
What are triacylglycerols?
This amino acid is the only one that is achiral and is often found in loops and turns due to its conformational flexibility.
What is glycine?
This basic level of protein structure involves hydrogen bonds between main chain atoms of the polypeptide backbone but does not involve side chain interactions.
What is secondary structure?
In the reaction mechanism catalyzed by RNase A, this residue acts as both an acid and a base to promote nucleophilic attack and cleavage of the RNA phosphodiester backbone.
What is histidine?
RNA is more susceptible to hydrolysis than DNA because of the presence of this functional group attached to the 2’ carbon of ribose.
What is a hydroxyl group?
This membrane lipid makes up 30-40% of all lipids in the plasma membrane and is used as a precursor in the synthesis of steroid hormones.
What is cholesterol?
This positively charged amino acid is often a target of modifications such as acetylation, methylation, and ubiquitination.
What is lysine?
This common secondary structural motif consists of two or more polypeptide strands hydrogen bonded to each other, with the strands being arranged in a parallel or antiparallel manner.
What is the beta sheet?
This metal ion has an important role in activating a water molecule for nucleophilic attack in the reaction catalyzed by carbonic anhydrase.
What is zinc?
Double-helical DNA is stabilized by hydrogen bonds, ionic interactions, and this type of van der Waals interaction, which is a result of the hydrophobic effect.
What are stacking interactions?
This class of membrane proteins requires harsh chemical treatments that disrupt membrane structure in order to be dissociated from cell membranes.
What are integral membrane proteins?
This side chain of this hydrophobic amino acid is the only one that contains a thioether linkage.
What is methionine?
This general class of proteins lacks three-dimensional structure and is rich in polar/charged amino acids.
What are intrinsically disordered proteins?
In the reaction mechanism of chymotrypsin, the catalytic triad is formed by a serine, a histidine, and this residue, all three of which are required for maximal activity of the enzyme.
What is aspartate?
This value, often used as a measure of the stability of a DNA molecule, is defined as the temperature at which half of the double-helical structure is lost.
This type of lipid has a double bond in the trans configuration and a fatty acid residue attached to its three-carbon backbone via an amide linkage.
What are sphingomyelins?
This natural sleep aid is the largest of the 20 standard amino acids and is also the least commonly found in proteins.
What is tryptophan?
This glycine and proline rich protein is a right-handed triple helix consisting of three left-handed helical polypeptides that wind around each other.
What is collagen?
This multisubunit enzyme is involved in the synthesis of pyrimidine nucleotides such as CTP and is regulated allosterically by ATP and CTP binding.
What is aspartate transcarbamoylase?
Double-stranded RNA segments most closely resemble the structure of this form of DNA, which has a helical sense diameter slightly larger than that of Watson-Crick DNA.
What is A-DNA?
Free fatty acids and single-tail detergents such as SDS form this type of structure in an aqueous solution due to the hydrophobic effect.
What is a micelle?