Alexander Fleming (1881-1955)

3

                                  Section of Pathology

73

suscepntible bacteria can be added to a solution of lysozyme and they are dissolved
untill the fluid becomes a stiff jelly, almost impossible to work with.

Lysozyme is not destroyed by acetone, alcohol, ether, chloroform or toluol, even
hen they have acted for a considerable time. These substances therefore can be
used for the preservation of lysozyme-containing materials. A very convenient way
of preservation of lysozyme is to dehydrate the tissue with acetone and then allow
it to dry.

Stability.—When kept dry, lysozyme can be preserved for a long time. It was
noted that commercial dried egg albumen was very rich in lysozyme but, of course,
the age of the dried albumen was not known. Recently I have tested a number of
samples of lysozyme-containing materials which had been kept for ten years dried
in a laboratory cupboard. These still contained lysozyme and, by the rough tests
employed, they seem to have lost little of their activity. The tissues examined were
spleen, liver, cartilage and egg (fish).

Fig. 1 shows the antibacterial action of pike’s eggs immediately after being dried,
and ten years later. The eggs were treated with acetone, dried, and stored in a
cupboard in the laboratory in an ordinary corked specimen tube. The eggs were

[NLS note: a graphic appears here – see image of page]

FIG. 1.—Pike’s eggs embedded in agar plates planted with M. lysodeikticus.
A—Pike’s eggs fresh. Experiment done in 1922.
B—Same batch of pike’s eggs kept in a cupboard for ten years. Experiment done in October, 1932.

imbedded in the same way in agar, and the same test microbe was used. One
experiment was done and the photograph published in 1922. The second was done
in October, 1932, and it is clear from a comparison of these photographs that after
ten years the inhibitory power of the eggs has not altered.

Preparation of lysozyme in a pure state. —In nature lysozyme is present in tissues
and secretions which contain proteins. The protein may be scanty as in tears, or
plentiful as in egg-white, and the fact that tears are very rich in lysozyme and at
the same time contain little protein, makes it obvious that lysozyme action is not a
function of the ordinary proteins of the body. Most of the protein precipitants
precipitate lysozyme at the same time. If a lysozyme-containing material, such as
sputum or nasal mucus, is treated with alcohol, the protein is precipitated along
with the lysozme. If this precipitate is collected, washed free from alcohol and then
shaken up in salt solution, the lysozyme will gradually dissolve in the salt solution
and will continue to diffuse out from the precipitated protein for some considerable
time.