The pKa of an acid depends partly on its environment. Predict the effect of each of the following environmental changes on the pKa of a glutamic acid side chain. (a) A lysine side chain is brought into proximity. (b) The terminal carboxyl group of the protein is brought into close proximity.

A. Decrease

B. Increase

Explanation:

A. A lysine side chain is brought into proximity:

lysine is basic in its nature, it would have to stabilize the electrostatic interaction and also weak interactions existing among the acidic amino acids and hydrogen bond. This would then reduce or decrease the pH and thus pKa of the protein.

B. The effect of this on pKA is an increase on the pKA. The carboxyl group is acidic. When it is removed, it would then cause the pKA to be increased. There would be accumulation of more negative change by basic amino acids increasing the pKA.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

a electronegativity decreases beacuse the size of nucleus is bigger.