Learn Turkish: Menfaatlerimizi korumak adına yeni bir önerge hazırladık. - We prepared a new motion in order to protect our interests.

Both mean "in order to protect", but -mAk adına is more formal and carries a nuance of "for the sake of" or "in the name of." You will frequently see adına used for purpose in official, political, or business contexts, which fits perfectly here with preparing a formal motion (önerge).

Why does menfaatlerimizi take the accusative case (-i) here?

It is the direct object of korumak (to protect). Even though korumak is an infinitive used to form a purpose clause, it still acts like a verb towards its own objects, so it requires its specific direct object to be in the accusative case.

Could we say menfaatlerimiz adına without the verb korumak?

Yes, but the meaning shifts slightly. Because adına acts as a postposition of representation with nouns, menfaatlerimiz adına would mean "in the name of our interests" or "on behalf of our interests." By using the infinitive korumak, the sentence clearly expresses formal purpose: "in order to protect."

I know teklif means proposal. Why use önerge here?

While teklif is a general word for an offer or proposal, önerge specifically refers to a formal "motion" or "resolution" submitted in a parliament, board meeting, or official assembly.