> Klotho is a transmembrane protein that, in addition to other effects, provides some control over the sensitivity of the organism to insulin and appears to be involved in ageing. ...
https://en.wikipedia.org/wiki/Klotho_(biology)
That means that you're probably not going to make a drug my injecting Klotho or with Klotho tablets. Instead, your best bet is to make small molecules that inhibit or promote the activity of Klotho.
Then the article compounds the problem with:
> Now Dr. Dubal and other researchers are trying to build treatments based on these results. Either by injecting Klotho into the body or by stimulating the brain to make more of the hormone, they hope to treat diseases like Alzheimer’s.
Later:
> When Dr. Dubal injects Klotho into mice, for example, the hormone doesn’t actually get into the brain. It must trigger some series of reactions in the body — but no one can say what they are.
This is why an injectable of the enzyme itself seem so unlikely:
1. Brain penetration is difficult to engineer into molecules, and especially so with proteins. Small tends to be a requirement, and peptides rarely fit the requirement.
2. An enzyme requiring to be bound in a membrane makes a terrible drug target because no only must it escape the body's housekeeping machinery, but must somehow survive with its membrane intact or miraculously become bound into the membrane of a passing cell. I'm unaware of any examples of that.