lab 6

Question 1

Phosphatases

Answer 1

a group of non-specific enzymes that catalyze the hydrolysis of a variety of phosphate monoesters to produce inorganic phosphate

Question 2

Alkaline phosphatases are

They occur in

Answer 2

• phosphatases that have maximal activity at a basic pH

- bacteria, fungi, and higher animals but not in plants

Question 3

E. Coli alkaline phosphatase
\_\_\_\_\_\_ Da
composed of \_\_\_\_\_\_\_ which must \_\_\_\_\_\_
pH optimum \_\_\_\_\_
pI \_\_\_\_\_
There are \_\_\_\_\_ present per enzyme

Answer 3

86 000
2 identical subunits
associate for the enzyme to be active
8.0
4.5
two zinc atoms

Question 4

Periplasmic space

Answer 4

• area between the cytoplasmic and outer membranes of the cell
• when e. coli alkaline phosphatase is excreted
• is impermeable to most phosphorylated compounds

Question 5

In the periplasmic space, alkaline phosphatase ________, which is then bound by _______

Answer 5

hydrolyzes Pi

a small carrier protein called the Pi-binding protein

Question 6

The Pi is transferred from the Pi-binding protein to the ________, which transports the phosphate ____________

Answer 6

Pst system

across the cytoplasmic membrane

Question 7

Why can akaline be purified to a relatively high degree by selectively releasing periplasmic proteins from the bacterium

Answer 7

There are relatively few proteins compared to the huge number of proteins in the cell

Question 8

the cytoplasmic membrane is reinforced with

But the outer membrane is very ______

Answer 8

cross-linked peptidoglycan

sensitive to osmotic shock

Question 9

lysozyme

Answer 9

can partially fragment the peptidoglycan mesh, so with osmotic shock, periplasmic proteins are released into the medium

Question 10

Most other components of the cell

Answer 10

remain enclosed by the cytoplasmic membrane in vesicles called spheroplasts