A hydropathy plot of the amino acid sequence of a membrane protein begins with a region of high negative hydrophathy, followed by three regions of high positive hydropathy, and ends with a region of high negative hydropathy. Each of the regions of high positive hydropathy spans around 25 residues. The first two regions of high positive hydropathy have a short region of negative hydropathy between them. The second two regions of high positive hydropathy have a far longer region of negative hydropathy between them.

Which (terribly sketched by Nathan) schematic below best fits with the description above?

Shown below is a Michaelis-Menten kinetics curve for a reaction carried out using an enzyme concentration of 1 nM (0.001 μM).

What is the k_cat value for this enzyme-catalysed reaction?

Type your answer as a number in units of min^-1 but do not type the units or any other characters except the number itself.

Shown below is a Lineweaver-Burk (double-reciprocal) plot for an enzyme-catalysed reaction.

What is the Km value for this reaction? 

(Type your answer in units of mM but do not type the units or any other characters except the number itself.)

The velocity of each of these reactions:

Shown below is a ribbon representation of the enzyme triosephosphate isomerase.

True or False, The region labelled "J" is the C-terminus.

The following sequence forms an amphipathic α-helix:

Ala-Val-Asn-Asp-Glu-Ile-Ser-Thr-Leu-Met-His-Arg-Val-Lys-Ser-Phe-Phe-Gly

In your mind (or by taking a photo, sketching it out, annotating on the screen, or doing-whatever-you-need-to-do-because-this-isn't-a-paper-exam-so-I'm-adapting-it-here-for-this-revision-quiz...), map the sequence onto the helical wheel shown below. The position of Ala-1 is already shown.

Which side of the helical wheel diagram represents the hydrophobic side of the helix?

Isoelectic focussing is an old but nevertheless useful technique of separating proteins along a gel strip containing an immobilised pH gradient.

In an experiment utilising this technique, a mixture of four proteins (with known pI values of: 9.3, 8.1, 6.5, and 4) was added to the gel strip and an electric field applied. Then, the gel was stained so that proteins could be visualised.

From the image below (where black ovals represent the stained and visualised proteins), which gel strip represents the one corresponding to the above mixture of proteins?

A researcher studying enzyme kinetics created the following series of Michaelis-Menten ("MM") and Lineweaver-Burk ("LB") plots, shown below, but forgot which MM plot went with which LB plot.

Can you help them out and correctly pair up the graphs?

The data below shows four different protein unfolding curves for the same protein but containing various mutations.

The protein is 280 amino acids long. The N-terminal region of the protein involves a cluster of hydrophobic amino acids critical for stabilising the overall structure of the protein. The C-terminal region contains a solvent-exposed pocket containing charged amino acids that, whilst not so critical for protein folding, play an important role in the protein's function.

The mutations studied were as follows:

• R247K
• F38V
• F38A

The wild-type (WT) version of the protein has been extensively studied and no mutation has ever been found that has improved stability.

Which condition corresponds to which version of the protein?

In the process of revising for BCH2011, you fell asleep (understandable) but upon awakening you realised you dreamt of the titration of an amino acid side chain (understandable). The details of the dream are murky, but you recall it looking something like this:

What is the pKa of the side chain and which amino acid were you dreaming of?